Industrial high precision lost-wax usually has a mold made from many layers, often either done in traditional monlith casting frames (big slabs of cement or plaster or casting sand or etc) or formed by dipping the parts into various cement slurries (a bit like a candle. The first few layers are generally a low-additive “print coat” made from ceramics akin to porcelain (that won’t react with the material being cast), and then for strength they’re bulked up with thick layers of stuff that usually has been bulked up with sand and recycled shells of precious castings that have been crushed down.)

It’s a fascinating process.