The back plate was heavy by about 7 grams, so I planed a bit off the left side where it was thicker. The graduation is now as it should be, and the weight is spot on at 121 g. That’s the usual target of 115 g plus an allowance of 6 g for linings. The belly is 81 g, 6 g over the target mass of 75 g.
The corner and end blocks are trimmed to size, but only approximately to height. I intend to make the plates non-coplanar, so I will adjust the block heights once the ribs are in place. The machined-in “linings” are trimmed back for the blocks.