I've decided to make several aluminum balls using lost-foam casting. Instead of the foam balls I took 3 ping pong balls. I wasn't sure if it would work right but finally it did.

Step 1: Putting Ping Pong Balls Inside a Saucepan

My flask was to small for this pattern, so I've decided to use a saucepan.

Step 2: Casting

When aluminum was melted I started to pour it but very slowly. These balls are very flammable.

Step 3: Nice Texture

In result, I see that these balls burning very different to the foam. The surface is not smooth but looks very good. They have a lot of micro-carving.