Silicone mould: A silicone mould is a flexible mould made by casting liquid silicone rubber around a master pattern, used to cast small batches of resin or wax parts.
RTV (room temperature vulcanising) silicone is poured around a master part and cures into a rubbery block. Its flexibility lets parts with small undercuts be pulled out without the sliding cores a steel mould would need. It copies the master’s surface closely, so the master’s finish matters: an SLA master is usually sanded first.
What it means for the price
A silicone mould is a cheap, fast form of tooling, made in days rather than weeks. Its cost is the silicone, the master and the labour. It has a short life, because each casting wears the surface and the resin slowly attacks the silicone, so its cost is spread over a small number of parts. Larger quantities need several moulds, which is where steel tooling starts to compete.
Example: a 2 kg block of silicone at €30 per kg, a €80 master and 2 hours of work at €40 per hour make a mould costing about €220. The figures are an example.
Common confusions
A silicone mould is not liquid silicone rubber (LSR) moulding, an injection process for making parts out of silicone. Silicone moulds are the heart of vacuum casting. Read vacuum casting vs injection moulding.
Go deeper: Vacuum casting vs injection moulding for low volumes