Stepped Tumbler/Mug - Mould for Slipcasting

Fully printed system to make plaster moulds. This produces a 3-part mould (2 sides and a small insert for the base) to cast round tumblers/mugs with a stepped design which allows them to stack inside each other securely.    You need to cast plaster in the larger mould two times for the sides, for every one cast of the small insert. This gives a complete plaster mould.   This print has been scaled to 112% to account for clay shrinkage, with most casting slips this should give a final tumbler size of 9cm diameter and 9.5cm height, or a capacity of around 400ml.    With any fully 3D printed mould, you’ll benefit from using a release agent on the base plate surface. I use a generic mouldmaker’s soap, but any product designed for plaster release should be fine. It needs around 1350ml of plaster for the side pieces and around 180ml for the base insert, and you can calculate the weight of water and plaster needed with this tool: Plaster Calculator You can get a much better cast surface, even if your plaster mix is full of air bubbles, by using a paintbrush to dislodge any trapped air from the surface. I would suggest that you pour plaster until the ornament surface is covered but it isn’t completely full, then get a relatively small paintbrush and move it around in the plaster so that you’re brushing all of the details on the base plate surface. This will dislodge air bubbles, and once dislodged they’ll float upwards. Once you’ve finished this, pour in the rest of the plaster. If you manage to avoid adding more air as you do it (just brush gently), you’ll eventually remove all the bubbles from the surface and get a perfect cast.