Got the blocks together and shaped and positioned on the bike. I need to make a top piece yet to tie it all together. It will be intentionally too thick for stability until I get the underbelly fiberglassed. Then I'll thin it down before glassing the topside.
The pieces of cardboard are spacers to keep the blocks away from the top tube about 1/4", allowing room for laying fiberglass over the foam.
I'll be sanding a radius on all the corners because fiberglass cloth doesn't like to lay over a sharp edge.