Had an old backgammon set and pieces were missing and/or broken. I thought it would be fun to design new pieces that had a concave edge so they are easier to pick up and move. Then I was looking at the flat surface on the top and thought it should have something cool to look at. Why not the Bitcoin logo?

Note: I also did a Ripple (XRP) version for the opposing player's pieces. You can find it here: https://www.thingiverse.com/thing:4767669