This shows a home-made mold I used Hydrocal in. It's built form foamcore with packing tape applied to act as 'hinges' but also to ensure the surface would release easily from the Hydrocal.

This image shows the Hydrocal setting up in the home made mold made of white foam core and packing tape. Because I did not know how much to mix, I also had a rock mold handy and poured the excess into that so it wouldn't get wasted.

Here is the home made Hydrocal structure after being pulled from the mold, having details scribed into it with a knife and painting.

Many of the interior details in this scene were also made from Hydrocal.