A practical, opinionated list from the people on this forum. The golden rule: if you cannot identify a material, do not put it in a laser.
Safe and rewarding
Diode (445–455nm): birch and poplar ply, basswood, walnut, oak, bamboo, MDF (with proper extraction), cork, veg-tan leather, cardstock, wool felt, denim, slate, cast acrylic (dark colours cut best), anodised and coated metals, powder-coated drinkware, coated glass.
Fiber (1064nm): stainless, aluminium, brass, titanium, mild steel, some plastics (ABS, some nylons). Does essentially nothing to wood and organics.
Never
- PVC / vinyl / PVC-backed "leatherette" — releases chlorine gas. Corrodes your machine and harms you. Much cheap faux leather is PVC.
- Polycarbonate (Lexan) — melts, flames, yellows.
- ABS on a diode — cyanide compounds, melted mess. (Fiber marking of ABS is a different, controlled case.)
- Fibreglass, carbon fibre — glass dust and resin fumes.
- Chrome-tanned leather — chromium compounds.
- Anything unlabelled.
Needs a trick
- Clear glass — coat it (wet newspaper or marking spray) or you get thermal-shock chipping rather than a frost.
- Bare metal on a diode — use a marking spray, or accept that you need a fiber source.
- Dark-on-dark materials — engrave contrast comes from surface change; test before you promise a customer.
When in doubt, post the supplier link on the forum. Someone here has probably already cut it.
LaserPecker publish their own documentation on this topic — worth reading alongside these community notes.
Official article