DIY Bimetal Cup Coaster. Aluminum + Copper Casting

I wanted to try bimetal casting for a long time and finally I've decided to do it. I was planning to make a cup coaster using 2 metals: aluminum and copper.

To make bimetal casting I have to melt metals (aluminum and copper) in 2 crucibles at a time.

As a mold, I used two pieces of pipes. One, which has a smaller diameter, is situated in the center and the second forms the outer wall.

After polishing, I've seen that the central copper circle started to move. It means that I have to use an adhesive to glue it.

To protect surfaces from scratching I glued a piece of leather on the bottom and of course I didn't forget about the central circle.

The weight of this bimetal cup coaster is 336 grams (0.7 lbs.). It's heavy and it won't move while using it. In my opinion, it's good. In conclusion, I'd like to say that it was successful bimetal casting even though aluminum and copper haven't been welded together.