← All guidesWith a good silicone mold in hand (see the mold-making guide), casting copies is where you get a matched set, a run in a custom colour, or a batch of spares. For dice, the usual material is two-part epoxy resin: it cures water-clear, is durable, and handles the thick pour and any inclusions well. UV resin is a faster alternative, but it is mostly used for thin layers and multi-tone effects rather than a whole die, since it does not cure a thick pour evenly.
Colour, pressure, and inking
Colour and effects come from what you mix in: mica or pigment powders (pearl and metallic looks), liquid pigments or dyes (solid or translucent tints), alcohol inks (swirls and galaxy effects), and glitter or small inclusions. Go easy - too much colorant can weaken the cast and cloud the detail.
As with the mold, pressure-casting crushes any bubbles for crisp, fully-formed numbers and edges. Keep the cast pressure at or below what you cured the mold at - around 3-4 bar (40-60 psi) is typical - and let it fully cure before releasing the pot. (The mold-making guide explains why you never cast above the mold's pressure.) Ink or paint the recessed numbers after demolding, then wipe the faces clean - the engrave depth DieVinci uses leaves a deep enough well for paint to sit in.
Finish a cast like a master. A demolded cast still carries the parting line and a little surface haze - sand and polish it flat against a glass plate, the same way you finish a printed master (see the finishing guide), so the faces stay crisp and planar. Remember that casting affects balance: a fully-filled, bubble-free cast in a uniform material keeps the die as fair as the master. Voids and trapped air shift the centre of mass.
Working safely
Liquid resins and silicones are workshop chemicals, not craft paint. Uncured casting resin especially - epoxy and UV alike - is a skin and respiratory sensitizer: careless repeated exposure can leave you allergic to it for good. A few habits cover most of the risk:
Ventilate. Work with airflow - an open window and a fan, or proper extraction. Resins and release sprays off-gas as they cure.
Gloves and eye protection. Nitrile gloves (not latex - latex also inhibits platinum silicone) and safety glasses when mixing or de-molding.
A respirator for extended work or sanding. A half-face respirator with organic-vapour cartridges and a particulate pre-filter; sanding cured resin makes hazardous dust, so wear it and wet-sand where you can.
Skip polyurethane casting resin for dice. It is rarely used for dice and is the most hazardous of the common resins - its isocyanates are potent respiratory sensitizers (and give off toxic gas in a fire). Epoxy or UV resin do the job without it.
Cured is far safer than liquid - but fully cure and wash as the resin maker specifies, and do not assume a cast die is food- or skin-contact safe unless that resin is rated for it.