Cast vs. Extruded Acrylic: What's the Difference?
Cast and extruded acrylic look identical on the shelf — both are clear, rigid, glass-like plastic — but they're made two different ways, and that changes how they cut, machine, and hold tolerance. Knowing which you have (or want) saves a lot of frustration on custom work.
How each is made
Cast acrylicis polymerized as a liquid between two plates of glass. That slow process gives a higher, more uniform molecular weight — which is what makes it machine and laser so well. Extruded acrylic is melted and pushed through rollers in a continuous sheet, which is faster and cheaper and produces very consistent thickness, but a softer material that behaves differently under heat and tools.
Side-by-side comparison
| Property | Cast | Extruded |
|---|---|---|
| Laser cutting / engraving | Clean cut, frosty matte engrave | Glossier, gummier kerf |
| Machining / routing / drilling | Excellent — chips cleanly | Can gum and melt |
| Thickness tolerance | Looser (±10% typical) | Tighter, very consistent |
| Chemical resistance | Better | Lower |
| Scratch resistance | Slightly better | Softer, scratches easier |
| Thermoforming / bending | Good | Good, lower forming temp |
| Cost | Higher | Lower |
Which should you choose?
For custom fabrication, machining, and especially laser cutting, cast acrylic is the better choice — it cuts and engraves cleaner, drills without gumming, and resists chemicals and crazing better. Extruded earns its place where tight, uniform thickness matters (press-fit assemblies, layered stacks) or where cost is the deciding factor on plain glazing. For most cut-to-size work, cast is worth the small premium.
On tolerance
Both are sold to a nominalthickness, but cast's runs looser (roughly ±10%). If your design depends on an exact gauge, read nominal vs. exact sizes and plan for the variation.
FAQ
What is the difference between cast and extruded acrylic?
Cast acrylic is polymerized between glass plates, giving better machining, laser cutting, and chemical resistance but looser thickness tolerance. Extruded acrylic is pushed through rollers, giving very consistent thickness and lower cost but a gummier laser cut and easier scratching.
Which is better for laser cutting and engraving?
Cast acrylic. It cuts cleaner and engraves with a frosty-white matte contrast, while extruded tends to leave a glossy, gummier cut edge with less engraving contrast.
Which is cheaper?
Extruded acrylic is generally less expensive to produce, but the difference is small at retail cut-to-size and is usually outweighed by cast's better machining and laser behavior for custom work.