Hi Andrew,
I found this to be an interesting challenge. But I think I figured out at least the first part. A body to mirror to make the full dodecahedron.
Start with a pentagon.
Make a copy of the pentagon by rotating from an edge 116.56505*.
Add a midplane between both pentagon sketches.
Rotate and copy the new plane 72*. Repeat 3 more times.
Extrude a body from the first pentagon sketch. Use the planes and Split Body tool to make the pentagon body for mirroring.
Select the body and mirror on any face until the dodecahedron is complete.
I’m using Shapr3D to design and build our house as well. It’s an amazing tool. Being able to build anything here first helps to find issues before costly materials and time are wasted. The topography was a fun modeling challenge as well.
