Among my dad's old tools was an unwieldy chunk of  beeswax covered in soot and dust. A bit of craft history. The bees that made this have all perished over half a century ago.

I'm processing the wax by melting it and molding it into handy little bars. For this reason I designed this small mold. Maybe you can use it for your own projects.

Print two and they will fit together to make one mold. PLA works fine. The mold hasn't deformed even after pouring in loads of hot wax.

UPDATE: PLA is fine for small runs but you might need something more durable if you're planning on doing a lot of casting. After casting 40 to 50 parts the mold was worn out and needed to be replaced.