This ended up taking longer than I expected. I had to delete a lot of overlapping faces in the mesh. I also had to reduce the number of faces dramatically to get it to import into Solid Works. Not a huge improvement over the original, but it will have its uses.
The chamfer plate is strictly for gluing to the underside of the lid to secure it better to the base.
Printed with the original tombs, and haunted by the ghost of Thyrik.