Tiers & Materials

A guide to what we make and how we make it.

The principle

We make six tiers because we make six different kinds of object. Each tier is a recipe — a combination of specific materials designed to work together in harmony with your hand to produce specific sensations.

Not every piece exists in every tier. Construction follows design intent: a piece exists in a given tier when that recipe is the right answer for what the piece needs to do.

Quick reference

Tier	Material	What it is
Good	ABS / ASA	Real engineering plastic, no aesthetic upgrade
Better	Vapor-smoothed ABS / ASA striking faces (with polycarbonate handles for hammers and Authority Figures)	Polished, often heavy, ~10–15% stronger
Ultimate	PA612-CF15 / Polycarbonate	Aerospace-grade engineering polymers
Best	Polycarbonate (PolyMax PC)	Top of the standard line
Play Party	PA6/66	Sanitizable for events
Flexible	TPU 95A	Limited; flex is the point
Heritage	CNC aluminum	Inquiry only

Good — ABS / ASA

The entry point. Engineering thermoplastic, printed in our enclosed heated chambers using the same classes of ABS and ASA you'd find in automotive trim, power-tool housings, and outdoor signage. Fully fused, structurally sound, dimensionally stable. The mechanical promise is real.

What you give up at this tier is finish polish, not performance. Layer lines are visible. No vapor smoothing, no extra material density. The piece does what the design says it does — it just looks like a printed object instead of a finished one.

This is the tier for people who want the engineering and don't need the gloss.

Better — vapor-smoothed ABS / ASA

Take the Good-tier object and put it through a controlled acetone vapor smoothing chamber with activated charcoal filtration. Two things happen.

The visible layer lines disappear, leaving a surface that reads as polished plastic rather than 3D-printed plastic. That's the cosmetic upgrade.

Less visible but more important: the surface stress concentrators that give 3D-printed parts a reputation for fragility also get smoothed out. The result is ~10–15% more strength under impact load. The piece doesn't just look better — it performs better.

Most Better pieces are also printed heavy — about 30% above standard material density. Heavier in your hand, lower-pitched on impact, with a settled feel that distinguishes them from the lighter tiers. The heavy treatment is a tag, not a default; check each product to see if it applies.

Ultimate — engineering polymers

This is where we leave the maker-shop conversation. Polyamide (nylon), carbon-fiber-reinforced polyamide, polycarbonate — the same classes of material used in ballistic shields, aircraft components, and industrial machinery.

These materials demand a process most makers can't run. Twelve to sixteen hours of controlled drying at 110°C before printing. Enclosed chambers held at high temperature during the print. Post-process annealing schedules tuned to each polymer to maximize crystallinity and relieve internal stresses.

What you get for the trouble is a piece that performs to the rated specification of the material — not to the dimensions of the print. Strike feels different. Sustained load tolerance is different. Acoustic character is different.

Some Ultimate pieces use Spectrum-series transparent PCs imported from the EU. Those add the visual depth of cast resin to engineering-grade structure. They cost more — international shipping and tariffs on already-expensive material — and they look like nothing else.

Best — polycarbonate

One material, selected and tuned per piece. Polycarbonate is the toughest printable thermoplastic by impact resistance; we use Polymaker's PolyMax PC formulation because it's nano-reinforced for impact and rated among the toughest available.

Best-tier pieces don't necessarily weigh the most — some Better pieces, printed heavy, weigh more in your hand. The polish at this tier is in the dimensional stability, the visual depth, and the way the material absorbs and returns energy on strike.

If Better is more, Best is refined. Same family of mechanical promises, executed at the highest material standard the standard catalog reaches.

Play Party — sanitizable PA6/66

A different promise: this piece can be cleaned with isopropyl alcohol or quaternary disinfectants between uses. PA6/66 is engineering-grade and structurally serious — there's no mechanical compromise here. The material was chosen for the use case.

If you bring pieces to events where multiple people may use them, this is the tier. The trade-off is aesthetic register: PA6/66 prints in a more limited palette and reads more clinical than the Better and Ultimate aesthetics. That's the right choice for what these pieces are for.

Flexible — TPU 95A

The flex is the point. Thermoplastic polyurethane bends, returns, and absorbs in ways no rigid polymer can. We use Flexible for products where the flex serves the design — collars, certain paddles, a ruler, a few others. It's never a default option.

The material has its own visual register: matte, slightly rubbery, undeniably fetish-coded. It looks like what it does.

TPU is slow and expensive to print correctly. Flex pieces sit on the printer longer than rigid ones, at lower speeds and tighter tolerances. The price reflects what they cost to produce. Not every product comes in this tier — only the ones where it's the right answer.

Heritage — CNC aluminum

We make a small number of pieces in machined aluminum, fabricated through Xometry from our designs. These exist outside the standard catalog and are sold by inquiry only.

If you're interested, contact us — we'll talk about what's possible.

Adjacent paths

A few things we make that don't sit on the tier ladder.

Mini-PETG

PETG is a polyester-class material — easy to print, widely available, balanced toughness and flexibility. We use it selectively for small-format pieces, where the geometry supports it and where price-of-entry matters. Mini Hephaestus drumstick pairs and Mini Mjolnirs are made in PETG. It isn't part of the tier ladder; it's a separate product class. Where PETG is the right material for a small form, we use it. Where it isn't — paddles, full-size impact surfaces — we don't.

B-Stock

Pieces with cosmetic flaws, retired designs, or small-batch inventory from tiers we no longer produce in. B-Stock is sold honestly: each piece has its specific story disclosed and its own price. The structural promise of the piece's tier still applies; only the cosmetic finish is compromised. Returns and warranty work the same way as the standard catalog.

Custom Shop

Bespoke commissions — a colorway we don't normally make, a configuration we don't list, a piece you've imagined and want to discuss. Custom Shop is inquiry-only and not configurable on the site. Tell us what you're after; we'll figure out whether and how we can make it.

What this all adds up to

Every piece we make carries a lifetime-of-the-business warranty. As long as Evil Engineering is operating, we'll repair or replace any piece that fails under normal use, with sensible exclusions for modification or abuse. We can promise this because we know the materials, we know the process, and we made the object. If something doesn't work, we want to know about it and we want to make it right.

We honor 30-day returns on standard catalog pieces. Custom Shop and Kelleynator full-size are made-to-order and excluded from returns; the terms are discussed at the time of inquiry.

Made-to-order is real here. Some of our materials need 12–16 hours of drying before they touch a print head. Annealing cycles run for days. Vapor smoothing is its own batch process. We don't fake fast shipping. Realistic lead times are stated on each product page — they protect both of us.

One maker, one workshop, six printers. Every piece passes through the same hands.

That's what a tier means here.

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The materials, in depth

If you want the deeper material-by-material reference, here it is — every polymer we work with, what it does, and where we use it.

Standard Polycarbonate (PC)

Polycarbonate is the backbone of our production line. It delivers exceptional impact resistance, high heat deflection, and a natural translucency that takes color beautifully. We run multiple PC formulations and have dialed each one to our enclosed, heated-chamber printers for consistent, high-quality results.

Keyboard Components: An excellent choice for keyboard cases and housings. PC provides a satisfying, slightly deeper acoustic profile compared to PLA or PETG, with the structural rigidity to hold threaded inserts and handle daily use without creep or fatigue.

Impact Toys: Our standard material for impact toy handles and a strong option for heads. PC's combination of stiffness and impact resistance makes it ideal for components that must endure repeated dynamic loading without cracking or deforming. Handles printed in PC are genuinely over-engineered — these are not fragile prints.

Functional Parts: A go-to engineering material for jigs, fixtures, brackets, and replacement parts that face mechanical stress or moderate heat. Suitable for demanding environments where PLA or PETG would soften or fail.

Polymaker PolyMax PC

PolyMax PC is a nano-reinforced polycarbonate engineered specifically for impact resistance — Polymaker rates it among the toughest printable thermoplastics available. We call this material out by name because its performance in impact applications is in a class of its own.

Keyboard Components: A premium option for cases where maximum durability matters. PolyMax PC is overkill for a keyboard that lives on a desk, but for travel cases, portable builds, or customers who simply want the toughest possible housing, it delivers.

Impact Toys: This is our top-tier head material. Where standard PC is already excellent, PolyMax PC provides an additional margin of impact absorption that makes structural failure genuinely absurd. When we say our premium products are over-engineered, this material is a big part of why.

Functional Parts: Ideal for any application where impact loading, vibration, or repeated stress cycling is a concern — tool handles, guards, protective housings, and high-abuse fixtures.

ABS

ABS is one of the most widely understood engineering plastics, and for good reason. It's stiff, reasonably tough, prints reliably in our enclosed heated chambers, and — critically for certain product tiers — it can be acetone vapor smoothed to a glossy, injection-molded finish.

Keyboard Components: A solid choice for cases and housings, especially when a smooth, finished aesthetic is desired. Vapor-smoothed ABS cases have a polished look and feel that's difficult to achieve with other FDM materials without extensive hand finishing.

Impact Toys: ABS serves as our standard-tier material for impact toy heads, offering good rigidity and durability at a lower price point than PC. Vapor smoothing also eliminates the micro-notches between layer lines that act as stress concentrators, providing a measurable strength improvement beyond the cosmetic benefit.

Functional Parts: Well-suited for general-purpose fixtures, housings, and replacement parts. ABS is easy to post-process, bonds well with adhesives and solvents, and is a proven workhorse in functional applications.

ABS-GF (Glass Fiber Reinforced ABS)

Glass fiber reinforcement increases ABS's stiffness and dimensional stability while reducing warping during printing. The result is a material that holds tight tolerances and resists deformation under sustained load.

Keyboard Components: An excellent option for larger cases or designs with thin walls where standard ABS might flex. The added rigidity improves acoustic consistency and structural feel without a significant weight penalty.

Impact Toys: A reliable middle-tier material. ABS-GF provides noticeably more rigidity than standard ABS, making it well-suited for handles and structural components where stiffness matters. It does trade some of ABS's raw impact toughness for that stiffness, so we pair it with appropriate head materials accordingly.

Functional Parts: One of our most versatile production materials. The improved dimensional stability makes ABS-GF particularly good for jigs, fixtures, and precision components where tight tolerances and resistance to creep are priorities.

ASA

ASA is functionally similar to ABS but with significantly improved UV resistance and weatherability. Where ABS will yellow and become brittle with prolonged sun exposure, ASA maintains its color and mechanical properties outdoors.

Keyboard Components: Suitable for keyboard cases, though the UV advantage is rarely relevant for a device that lives indoors. We'd typically recommend ABS or PC instead unless there's a specific need.

Impact Toys: Not a primary material for this application. While ASA is mechanically similar to ABS, we haven't found a compelling reason to use it over ABS or PC for products that are used and stored indoors. Available on request for customers with specific requirements.

Functional Parts: The clear winner for any outdoor or UV-exposed application — enclosures, brackets, signage, garden fixtures, or anything that will see sunlight. If your part lives outside, ASA is likely the right material.

PETG

PETG is our accessibility-tier material — easy to print, widely available, and offering a solid balance of toughness and flexibility. It's the material that makes our small-format Mini line possible.

Keyboard Components: A budget-friendly case material with decent impact resistance and a slight flex that some users actually prefer acoustically. PETG won't match the rigidity or heat resistance of PC, but for a standard desk keyboard it performs well.

Impact Toys: PETG is the material behind our small-format Mini impact products (Mini Hephaestus, Mini Mjolnir). These are priced for accessibility and intended as an introduction to our designs. PETG handles repeated impact well at small scale, but it lacks the stiffness and heat resistance of our standard and premium tiers, so we don't use it for full-size pieces. See Mini-PETG above.

Functional Parts: Good for general-purpose parts that don't face high heat or heavy sustained loading. PETG's chemical resistance makes it a practical choice for parts exposed to cleaning solvents or mild chemicals.

PETG-GF (Glass Fiber Reinforced PETG)

Glass fiber reinforcement addresses PETG's main weakness — its tendency to flex under load. PETG-GF offers improved stiffness and dimensional stability while retaining much of PETG's ease of printing and chemical resistance.

Keyboard Components: A meaningful step up from standard PETG for cases. The added rigidity gives it a more solid feel and better acoustic profile, closing much of the gap between PETG and PC at a lower price point.

Impact Toys: Not a standard material in our impact toy lineup. While the glass fiber improves stiffness, the base PETG matrix still lacks the heat resistance and long-term fatigue performance we require for products built to take real abuse. Available on request.

Functional Parts: A practical upgrade over standard PETG for fixtures and brackets where stiffness matters but the full cost and processing requirements of PC or nylon aren't justified.

PET-CF (Carbon Fiber Reinforced PET)

PET-CF combines the printability of the PET family with the stiffness and weight reduction of carbon fiber reinforcement. The result is a lightweight, rigid material with a distinctive matte carbon fiber texture.

Keyboard Components: An excellent option for customers who want a premium, lightweight case with a distinctive look and feel. The carbon fiber texture provides a unique aesthetic straight off the printer, and the stiffness-to-weight ratio is outstanding.

Impact Toys: Not a primary material for heads or striking surfaces — carbon fiber composites are stiff but can be brittle under sharp impact. However, PET-CF is a viable option for handles and structural components where stiffness and light weight are priorities over impact absorption.

Functional Parts: Well-suited for applications demanding high stiffness at low weight — drone components, instrument housings, and precision fixtures where dimensional stability is critical.

Fiberon PA12-CF20

Fiberon's PA12-CF20 is a nylon 12 base reinforced with 20% chopped carbon fiber. This is a serious engineering composite — stiff, strong, dimensionally stable, and capable of handling sustained mechanical stress in demanding environments. We call out the Fiberon brand here because formulation matters with filled nylons, and this one has earned its place in our production workflow.

Keyboard Components: A premium-tier option for customers who want the absolute stiffest, most dimensionally stable case available. PA12-CF20 produces a distinctly solid, almost metallic feel and an unmistakable matte carbon fiber surface texture.

Impact Toys: Our top-tier handle material. The carbon fiber reinforcement provides the stiffness needed to transmit energy cleanly through the handle without flex, while the nylon 12 matrix provides enough toughness to absorb shock without cracking. On our premium PA-CF handles, the slight protrusion of carbon fibers also creates a subtle micro-texture that enhances grip. The full production process for these handles spans multiple days — drying, controlled printing, annealing, and moisture conditioning — and the result justifies every hour.

Functional Parts: The material of choice for high-performance jigs, fixtures, and components that must hold tight tolerances under load and over time. Excellent creep resistance, low moisture sensitivity relative to PA6, and outstanding fatigue life.

PA6-GF (Glass Fiber Reinforced Nylon 6)

PA6-GF pairs the toughness and wear resistance of nylon 6 with glass fiber reinforcement for improved stiffness and reduced warping. It's a robust engineering material, though it requires careful moisture management and a fully enclosed, heated printing environment.

Keyboard Components: A strong candidate for cases where durability and wear resistance are top priorities. PA6-GF produces a smooth, professional-looking surface and holds threaded inserts exceptionally well. It does require proper drying and storage protocols to maintain quality.

Impact Toys: Suitable for handles and structural components where stiffness and wear resistance are priorities. PA6-GF offers a different balance from PA12-CF — more toughness from the nylon 6 matrix but less stiffness than carbon fiber reinforcement. It's a strong option where some flex in the handle is acceptable or desired.

Functional Parts: Excellent for wear-prone components — bushings, guides, sliding surfaces, and load-bearing fixtures. The glass fiber reinforcement provides the stiffness to hold tolerances while the nylon base delivers the wear resistance that makes the parts last.

PA12-GF (Glass Fiber Reinforced Nylon 12)

PA12-GF combines nylon 12's low moisture sensitivity and dimensional stability with glass fiber reinforcement for improved stiffness and wear resistance. Compared to carbon fiber reinforced variants, PA12-GF offers better toughness and impact resistance at the expense of some stiffness — a trade-off that makes it the better choice for applications where the part needs to absorb energy rather than just resist deflection.

Keyboard Components: A durable, dimensionally stable case material with good resistance to wear and creep. PA12-GF produces a clean matte surface and holds tolerances well, making it a strong option for cases with snap-fit features or integrated mounting points. Its lower moisture absorption compared to PA6-based nylons means less dimensional change over time in varying environments.

Impact Toys: A versatile option for both handles and heads. The glass fiber reinforcement provides sufficient stiffness for clean energy transfer through handles, while the nylon 12 matrix's toughness gives it better impact absorption than carbon fiber variants — making it one of the few filled nylons we'd consider for striking surfaces as well as structural components. Like all our nylon products, PA12-GF parts go through our full multi-day drying, printing, annealing, and conditioning workflow.

Functional Parts: An excellent all-around engineering material for parts that face a mix of mechanical demands — moderate stiffness, good impact resistance, wear resistance, and chemical compatibility. Particularly well-suited for fixtures, guides, and components in environments where PA6 would absorb too much moisture and carbon fiber composites would be unnecessarily brittle.

Fiberon PA612-CF15

Fiberon's PA612-CF15 is a nylon 6/12 copolymer reinforced with 15% chopped carbon fiber. PA612 sits between PA6 and PA12 in chemistry and behavior — it gives up a small amount of stiffness relative to PA6-based composites in exchange for dramatically better moisture stability, which makes it the right choice for parts that need to perform reliably across humidity swings without elaborate conditioning protocols. We call out the Fiberon brand here because formulation matters with filled nylons, and this one has earned its place as our Pacific Northwest workhorse.

Keyboard Components: A premium engineering option that delivers most of what PA12-CF20 offers — solid feel, dimensional stability, matte carbon-fiber surface texture — with a little more matrix toughness. Slightly less metallic in hand, slightly more forgiving acoustically.

Impact Toys: Our Ultimate-tier handle material and the material behind every Authority Figure. The 15% fiber load is enough to transmit force cleanly through the handle without meaningful flex, while the tougher matrix absorbs vibration through long swings without fatigue accumulating in the structure. PA612 absorbs a fraction of the moisture that PA6 does, so unlike our PA6-CF20 head material, these handles don't require deliberate water conditioning after printing.

Functional Parts: The right choice when a part needs to hold its dimensions reliably in a humid shop, a damp basement, or any environment where PA6 would creep out of tolerance over time. Excellent fatigue life, good chemical resistance, and a surface that looks great.

PLA

PLA is the most widely printed material in the world for good reason — it's easy to print, available in an enormous range of colors and specialty finishes, and produces excellent surface detail. However, its mechanical and thermal limitations are real and must be acknowledged.

Keyboard Components: A viable option for decorative keycaps or low-stress cosmetic components, especially in specialty finishes (silk, sparkle, matte) that aren't available in engineering materials. We do not recommend PLA for structural keyboard cases due to its tendency to creep under sustained load and its low heat deflection temperature.

Impact Toys: Not used. PLA is too brittle under dynamic impact loading and too prone to creep and deformation for any product designed to take repeated abuse. We won't put our name on a product that might shatter during use.

Functional Parts: Suitable for prototyping, visual models, and low-stress applications only. If the part will see sustained load, heat, or impact, we'll recommend an appropriate engineering material instead.

PBT (Polybutylene Terephthalate)

PBT is well known in the keyboard world as the gold-standard injection molding material for keycaps — and for good reason. It offers excellent chemical resistance, low moisture absorption, a pleasant matte surface texture, and outstanding resistance to shine and wear. FDM-printed PBT is still a developing frontier, but we've been working with it.

Keyboard Components: The natural choice for printed keycaps and key-adjacent components. PBT's resistance to skin oils and finger shine is the reason it dominates the injection-molded keycap market, and those properties carry over to printed parts. It also produces a distinctive sound signature — denser and lower-pitched than PLA or ABS.

Impact Toys: Not used. PBT doesn't offer the impact resistance profile we need for products under dynamic loading. It's a great material for the right application, and impact toys aren't it.

Functional Parts: Useful for components exposed to chemicals, solvents, or repeated skin contact where surface degradation is a concern. Its low moisture absorption also makes it a good choice for parts in humid or wet environments.

PC-PBT (Polycarbonate / PBT Blend)

PC-PBT blends combine polycarbonate's impact resistance with PBT's chemical resistance and dimensional stability. The result is a balanced engineering material that performs well in environments where pure PC would be vulnerable to chemical attack.

Keyboard Components: A solid all-around case material that combines good acoustics, impact resistance, and resistance to skin oils and cleaning solvents. It's a practical choice for customers who want PC-level performance with better long-term surface durability.

Impact Toys: A viable alternative to standard PC for heads and handles, particularly for customers who want improved chemical resistance — relevant for products that may be cleaned frequently with various disinfectants and solvents. The impact resistance is slightly lower than pure PC but remains well within safe margins for our designs.

Functional Parts: An excellent choice for parts exposed to chemical environments — cleaning equipment, lab fixtures, food-adjacent components, or anything that needs to survive regular solvent contact without degrading.