I installed the foundation "stones" last night. This took a surprisingly long time to do. The paper swelled due to the glue, but shrunk back down as it dried, so the spacing was preserved. I'm going to try piping the grout because I don't want too much of it on the stone's surface, so that's the next step for this part.
I worked on starting the shingles too, but had to strip them off this morning as a total fail.
The daylighting really shows how thin the first paint layer is. It needs additional coats.