Today we did a bit more fine tuning on the gutters and hatch rims.
Then we meticulously glued together all the pre-rabbeted hatch rims, affixing the joints with five-minute epoxy in the gutters precisely where they will live. Then we carefully unscrewed the hinges and lifted them out.
We laid them upside-down on plywood, marked the shapes of the insets, cut them out, and ground them to fit.

And then came the clamp storm.
I just got a dozen more and I still don’t have enough.
Grandpa said "don't buy an old house". He also said – "never had enough clamps" to which the corollary is – "and never had a good enough place to put them". The lesson – make a room and they will come.