I have some questions about some points in here? will start with just some.
how do you sand off only the bondo and not any slate??
Bondo is softer than slate, so it sands off first.
What happens when you free the slates where they were bonded with superglue?
If you score the seams first with a razor knife, they come apart easy, and won't chip the slates
wood shims will only have 2 points in the table, one on the slate and one on the frame and they will be on an angle right? why do they make frames flat if they are going to be shimmed with an angled shim? Would you use angled shims between the pedastels and frame irons on a GC 1, I don't think so, I wouldn't.
The shims I use are long, and only slightly tapered, so they fit good, and it's easier to raise the surface of the slate that needs to be adjusted by tapping in the shim than it is to try and lift the slate to place another flat shim
I only see one machinst level and one carpenter level, its impossible to view a puzzle without having a picture of it together. Isn't it better to have more levels instead of writing all over the slate?
I demonstrated this leveling with one machinist level for the reason that not all mechanics have more than one level, nor do home owners