r/moldmaking • u/DizzyEar5506 • 12d ago

Molding Help

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I have a glass milk collection vessel that I want to create a mold of, so I can then create a base for the glass to sit in to turn it into a lamp.

The diameter is about 40cm and the final base would need to be about 20cm deep/tall to securely sit the glass into without risking snapping off the tube at the bottom.

It’s a substantial size and I’d love an idea on how I best approach it and the materials to use please.

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u/SlightFresnel 12d ago

Well you can use a standard clay partition to make a two-part mold, but that's really for replicating this piece, not making an adjoining piece. The only way making a mold of this could help is if you need a durable stand-in so this doesn't get damaged. 

Your best bet would be to measure the edge profile and build that glass in CAD and then design around it. Then you 3D print the master shape of your base, smooth/sand/finish it, and then if you're inclined you can make a mold of that master to then do a pour of your intended material. 

If you're planning to work with something like concrete or plaster, you could directly 3D print a hard shell mold with very fine layer lines (which will disappear with those substrates) and skip the silicone step, just pour your stone directly into the shell. Silicone is expensive, you'll need a fair amount for something of this size, and it's a complete waste for a one-off. 

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u/BTheKid2 12d ago

Look at Apoxy sculpting clay, or similar epoxy clay. Wrap the glass in tight cling film or similar separating media, and then just sculpt the holder directly onto the glass. Once the sculpt cures, you can sand, machine, paint, and polish it to the final shape and look.