Finally managed to finish the excavated dodecahedron!
First I made another six pentagonal units.
Then I stitched them together to form the second half.
Then I joined the two halves to form the complete dodecahedron.
It is a little wonky – it was tricky to get all the pentagonal units exactly the same size. And some of the joining could have been neater, though it was tricky making the final joins, as I had no access to the needle on the back side.
But I’m pretty pleased with it as a proof of concept. 🙂