A decision tree from "indoors, no load" to "replaces machined metal" — every material we stock, and the honest reasons to pick each.
Material choice looks like a twelve-way decision but usually isn't. Ask three questions: Does it live outdoors or somewhere hot? Does it carry real load? Does it need to flex? Each "no" keeps you cheaper; the first "yes" tells you where to spend.
All twelve materials, prices and full specs live on the materials page — this guide is the reasoning layer on top.
$0.099/g — the default prototype
$0.11–0.15/g — weather and UV
$0.22–0.28/g — the workhorses
$0.19/g — seals, feet, grips
PLA is the right answer more often than its price suggests: stiffest of the commodity plastics, crispest detail, least shrink (so it measures closest to CAD), and the cheapest per gram. Fit checks, form models, housings that live on a desk — PLA, no apology. Its limit is heat: it softens around 55 °C, which rules out cars in the sun and anything near machinery that runs warm.
PLA Matte trades a little toughness for a soft, even surface that hides layer lines — the pick when the part is the product photo. PLA-CF adds carbon stiffness for jigs and fixtures that must stay dead flat but never leave the workshop.
PETG is the sensible default for functional parts: tougher than PLA, shrugs off water and most cleaners, handles 70 °C, and prints reliably at 256 mm scale. Brackets, fixtures, enclosures, outdoor hardware under cover — PETG. PETG-CF stiffens it for structural parts that also face humidity.
ABS and ASA take heat into the high 90s. ASA is the outdoor one — UV-stable, keeps colour and toughness in the sun, the pick for anything living on a roof, a fence, or a vehicle. ABS's party trick is vapour smoothing: a sealed, glossy, water-tight surface that reads injection-moulded. PC is the strongest rigid material we run — guards, housings, load-bearing parts that also see heat — at the cost of a few dollars more per part.
TPU 95A is rubber-like: gaskets, grips, bumpers, vibration feet, anything that seals or absorbs. Design it twice as thick as feels right — flexible parts do their job through bulk.
PP is the chemical-and-fatigue specialist — living hinges that flex thousands of cycles, containers for solvents and fuels. PA12 nylon is tough and slippery: gears, clips, wear parts. PA-CF is carbon-fibre nylon, stiff into the 170 °C range — the material for brackets that replace machined aluminium. For all three, talk to us about your load case if you're unsure; nylons in particular reward a quick sanity check before you commit a batch.
Because pricing is per gram, material choice is visible in dollars before you commit: the same 75 g bracket is about $7.43 of material in PLA, $9.08 in PETG, $23.10 in PA-CF (GST included). Prototype in PLA, validate the design, then print the keeper in the engineering material — the two-step usually costs less than one over-specified first print.
Still torn between two? Quote both — changing material in the quote tool reprices live — or email hello@assysts.com with the part and its job, and you'll get a straight answer from the person who'll print it.
Prototype in PLA, ship in PETG, reach for PA-CF only when the load is real. That sentence is 90% of material selection.
Drop an STL, STEP or 3MF and the quote applies every rule in this guide — mesh check included, GST included.