32mm x4 Sprue Goo Base Mold

https://www.reddit.com/r/Warhammer40k/comments/1825n8w/sprue_goo_base_molding/ - full instruction how to use this to make your own bases from sprue goo.

https://www.thingiverse.com/thing:6424358 - 40mm
https://www.thingiverse.com/thing:6330200 - 50mm