If you're willing to use a Dremel, you can directly turn it into a base. I might upload the non-foam version later

A lot of preparation has to be taken to turn this into foam, they just models to cover in mold material.
You can sell these parts with credit, preferably a link!

Scale: 470% works ok for me. Make sure to compare it to a file you know fits you!
Infill: very very low if foam
Supports: depends on infill