The basic steps to make an ice mould out of Sugru are
1. Design the pattern
2. Cut the pattern into acrylic
3. Stuff the sugru into the pattern
4. Remove the pattern
Step 1: Design the Pattern
Using your favourite CAD software, design the pattern you want to have as part of your ice cube.
Since acrylic is much thinner than the final size of the ice cube mould, design it in layers. We had 3 layers... one solid circle and two circles with our makerspace logo cut into it.
Step 2: Cut the Pattern Into the Acrylic
Having a cute kid watch the process will only make the final result better.
Step 3: Stuff the Pattern With Sugru
Stack the various plates of acrylic and glue them together. Then pack the sugru around it and inside the holes.
Step 4: Remove the Pattern
Wait for the sugru to dry, remove the acrylic, and fill with water. Freeze.