Materials and Consumables
Choosing material is a design decision, not a supply-closet errand. The same bracket in PLA, in PETG, and in plywood behaves differently, and picking wrong usually shows up as a broken part rather than a wrong-looking one.
What's actually on the shelf changes. Check with June (jpeters@universityprep.org) before you commit a design to a material you haven't seen in the room, and well before you need a quantity of it.
Filament
| Material | Behaves like | Reach for it when | Trade-off |
|---|---|---|---|
| PLA | Stiff, hard, slightly brittle | Most parts, prototypes, anything cosmetic | Softens in a hot car; snaps rather than bends |
| PETG | Tougher, slightly flexible, more heat-resistant | Parts that flex, get handled, or take load | Stringier; slightly fussier to print well |
| TPU | Rubbery and flexible | Bumpers, grips, gaskets | Slow to print; not for structure |
PLA is the right default for this class — it prints reliably and it's what you'll iterate in. Move up to PETG, a carbon-fiber filled filament, or ABS when a part has failed in PLA for a reason you can name, not preemptively — and check with June about what's on hand before you design around one. Bambu Lab's filament guide covers what each material needs from the printer, and their PLA and PETG pages go deeper.
Sheet goods for the CNC
- Plywood is the workhorse — strong, cuts cleanly, holds a screw. Quality varies, and cheap sheets have internal voids you'll only find by cutting into one.
- MDF is flat, uniform, and cheap, with no grain to tear out. It makes the worst dust in the shop (mask up, see PPE), swells if it gets wet, and holds screws poorly in its edges.
- Plastic sheet cuts well with the right bit and settings. Ask before running any plastic you didn't get from the shop — some plastics melt onto the bit, and melting plastic releases fumes you don't want to be near.
The number that matters is the measured thickness, not the label. See Designing for the CNC.
Paper, card, and cardboard
Underrated, and the fastest material in the building.
- Cardstock takes fine detail on the Silhouette and is good for templates, patterns, and drilling guides.
- Corrugated cardboard is the test-fit material. Cutting a full-size cardboard version of a part before it goes on the CNC is the single cheapest way to catch a dimension error — see Vinyl and Cardstock Cutting.
Use these freely. That's what they're for.
Vinyl
- Heat-transfer vinyl (HTV) for fabric, applied with the heat press. Cut mirrored.
- Adhesive (sticky) vinyl for hard surfaces — labels, logos, bin markings. Applied with transfer tape.
Hardware
We stock general-purpose fasteners: wood screws, machine screws and nuts, and washers. For anything specific — a particular length, a drawer slide, a hinge, a specialty fastener — assume it has to be ordered and tell June a week before you need it, not the day your team reaches that step. An ordered part arriving late is one of the few delays no amount of good work recovers from.
Electronics
LEDs, batteries, and basic circuit components are available, and there's some capacity for microcontrollers if a project genuinely calls for one. Talk to June before designing electronics into a project so the scope stays realistic alongside the fabrication work.
Using material well
- Prototype in the cheap material. Cardboard, then scrap plywood, then the good sheet. Never let your first attempt at a part be on your only piece of nice material.
- Nest your parts. Lay out cuts to use the sheet efficiently rather than cutting one part out of the middle.
- Keep your offcuts. The scrap bin is where test coupons and second attempts come from — for you and for everyone else.
- Label your material. An unlabeled half-sheet on the rack becomes shared scrap.