couple of questions1. what infill did you use for the base if your adding salt/sand as ballast
2. Don't understand how the Stab fits to the top base. You mention heat inserts but there's no where for a M6 bolt to go through?

Lastly, you've written you need a 40/30 7mm bearing.
while the 30 Inner diameter tracks out, 40mm is too small. Test piece is 42mm and even the actual model is 42mm (edited)