One of the questions I get asked the most after people build their own vacuum forming machine is: "which plastic should I actually use?" It is a fair question — the wrong sheet can warp, tear, or simply refuse to form around your mold, no matter how good your machine is. Here is a rundown of the most common options and where each one shines.
ABS (Acrylonitrile Butadiene Styrene)
ABS is the classic choice for hobbyists and one of the easiest plastics to vacuum form at home. It heats evenly, holds fine detail well, and is tough enough for functional parts like enclosures, cosplay armor, or prototype housings. It is a great starting material if you are still getting a feel for your machine's heating and vacuum timing.
- Pros: easy to form, good detail, widely available, paintable
- Cons: not food-safe, not very heat or UV resistant long-term
PETG
PETG has become very popular for vacuum forming because it strikes a nice balance between strength and ease of use. It is more impact-resistant than ABS, food-safe (important for trays, molds for candy, or packaging mockups), and forms with a slightly glossier finish.
- Pros: food-safe, impact-resistant, good clarity in thin sheets
- Cons: can stick to molds without proper release/dusting, needs slightly more heat control than ABS
HIPS (High Impact Polystyrene)
HIPS is a favorite for large, thin parts — think signage, model railroad scenery, or lightweight props. It is inexpensive and forms quickly at lower temperatures, which makes it forgiving for beginners working with smaller or improvised machines.
- Pros: cheap, fast to form, lightweight
- Cons: brittle over time, less durable for parts that take repeated stress
PVC
Rigid PVC sheet is a good option when you need extra chemical resistance or a slightly stiffer finished part. It is commonly used for signage and outdoor-facing pieces, though it requires good ventilation when heated.
- Pros: chemical and weather resistant, rigid
- Cons: needs proper ventilation when heating, less common in hobby sizes than ABS or PETG
Choosing the right sheet thickness
Thickness matters as much as the material itself. As a general rule for a homemade machine:
- 0.5mm – 1mm: good for small, detailed molds and first tests
- 1mm – 2mm: the sweet spot for most hobby projects — enclosures, props, trays
- 2mm and above: needs a stronger heater and more vacuum power, better suited once your machine is dialed in
If you are just starting out, thinner sheets are more forgiving: they heat faster, need less vacuum strength, and let you learn how your specific machine behaves before committing to thicker, pricier material.
A note on your machine
The plastic is only half the equation — how evenly your machine heats the sheet and how quickly it pulls vacuum makes just as much difference to the final result. If you have not built your machine yet, my eBook walks through the entire process step by step, from raw materials to a working setup, with hand-drawn diagrams for every stage.