Thermoset plastics and resins
Unlike thermoplastics, resins and thermosets don't soften with heat: once cured, they stay that way. They're cast, printed by photopolymerisation and moulded, but rarely cut or milled like a sheet.
How to read the table
3D printing — “Yes” means resin printing (SLA/DLP), not FDM: thermosets aren't melt-extruded. Laser — generally “No” on composites and thick resins. CNC — possible on cured composites, but with mandatory extraction for fibre dusts. Across the whole family, safety (liquid resins, dusts, solvents) weighs more than technical feasibility.
Epoxy resins
Two-part resins for casting, structural bonding and coatings. They're poured into moulds or used as adhesive, not cut from a slab. While liquid they're irritants: gloves and ventilation until full polymerisation.
| Material | Laser | CNC | 3D printing | Food safe |
|---|---|---|---|---|
| Epoxy casting resin (low viscosity) | No | Yes | No | No |
| Epoxy laminating resin | No | With limitations | No | No |
| Structural epoxy resin (adhesive) | No | No | No | No |
| UV epoxy resin | No | With limitations | Yes | No |
Polyurethane resins
Fast casting resins, often for reproductions and prototypes from silicone moulds. Some systems contain isocyanates: ventilation and respiratory protection are necessary during casting.
Photopolymer resins (3D printing)
Resins for SLA/DLP/MSLA 3D printing. Liquid and uncured they irritate skin and airways: nitrile gloves, ventilation, washing in isopropyl alcohol and final UV curing. They give high detail, in exchange for a more careful workflow.
Silicones
Two-part elastomers used mainly to make flexible moulds from which to cast resins. They're poured, not cut or milled. Food-safe silicones and technical silicones exist: the intended use depends on the specific product.
| Material | Laser | CNC | 3D printing | Food safe |
|---|---|---|---|---|
| Two-component RTV silicone | No | No | No | No |
| Mould-making silicone (addition cure) | No | No | No | Finished only |
| Mould-making silicone (condensation cure) | No | No | No | No |
Thermoset composites
Cured carbon and glass fibre in an epoxy matrix. They mill but generate fibre dusts that are dangerous to breathe: extraction and mask mandatory. On the laser they don't cut cleanly (the matrix burns, the fibres don't).
| Material | Laser | CNC | 3D printing | Food safe |
|---|---|---|---|---|
| Corian and solid surfaces | With limitations | Yes | No | Yes |
| Carbon fiber + epoxy (CFRP) | With limitations | Yes | No | No |
| Glass fiber + epoxy (GRP) | With limitations | Yes | No | No |
| FR4 (Glass-Epoxy Laminate) | With limitations | Yes | No | No |
Working with Thermoset plastics and resins: what to know
The logic of this family is “pour and cure”, not “cut from a slab”. Epoxy and polyurethane resins are cast in moulds or used as structural adhesives; silicones serve mainly to make the moulds themselves.
Photopolymer resins deserve the most careful chapter, because they're the basis of resin 3D printing (SLA, DLP, MSLA). Uncured liquid resin is an irritant to skin and airways: you work with nitrile gloves, in a ventilated space, avoiding direct contact; parts must be washed (usually in isopropyl alcohol) and then cured under UV light. It isn't a hostile material, but it's one that demands discipline.
Cured thermoset composites, such as carbon or glass fibre in an epoxy matrix, can be milled but generate dangerous dusts: the respirable fibres require extraction and a proper mask. On the laser, generally, they don't cut cleanly (the matrix burns, the fibres don't).
In short: here 3D printing means resin (not FDM, because the material isn't melt-extruded), laser cutting is almost always excluded, and milling is possible but subordinate to dust management.