* For the machine shop roof I cut a attic floor out of wood with my exacto knife. I used it to cut everything. When first cut to a matching shape it laid down flat and I was happy. Now as with all the sections I cut out for the roundhouse roof they fit very well. Once I glued them down the glue did something to the seams as it hardened. It caused distortion in the roof sections. Seams that when first cut, that were perfectly aligned, when laid in the curing glue would move. Pushing the edges together sometimes causing the edges to overlap. At first i thought the were swelling the cardstock but it seemed to be the opposite. Like a shrinking because this would distorted the floor, pulling up the edges. When you placed the roof back in its recess, it would not lay flat anymore. When you pressed down on a raised corner the opposite corner would raise up. That is why it took over 3 weeks to build that roof, and I was constantly adding a thicker floor and popping the seams open and re-gluing the seams. Right now there are two continuous seams going from front (door side) the back (curved wall side) open and not glues. The roof now lays flat on its three layer floor, and I am not happy with it but will live with it.
* Now getting back to the machine shop roof. I glued it. it shrank and became a wobbly surface, now unreliable, and I replaced it with a card stock floor of two layers thick. This i may have to thicken up with a third layer. I do not know now at this time. Lets see what happens.
frank