I have attempted to make a complex cast using a mould of paper and two different kinds of sand/stone/gravel inside and outside of the mould. I laser cut the mould itself to attempt to replicate a shape previously generated in a computer. The first thing I did was to do a series of experiments to see what recipe I should follow.
From this I gattered that I should keep the part of water over 0.8:1 maybe even 1:1 if it’s a deep cast. I used a part of our group project as the design for my mould, it is a series of walls subdividing a large space. The model I was going to make is quite hard to cast – it is thin walls in odd angles, so it’s a definite challenge. I started by using the unroll command on the 3D-model in Rhino and laser cut the resulting pieces.
When I started building the mould I realized it would have been impossible to make this thing water tight and so this technique is not only convenient but also may be crucial to the success of this cast.
When I demoulded my cast parts of it started breaking apart in one place. As my group looked back on our design, we decided to redesign the part that broke off to make it less fragile. The largest part of the model still held together better than expected since I knew the walls where almost too thin. The walls became a little wobbly, this is because of deformation that has occurred as the mould was being filled. It would probably be better to use a little sturdier paper, maybe even a 1 mm cardboard instead for this kind of mould.