Dunno what these are called; rather than a foundation, this is the underside of the house's floor, turned upside down. The little piers hold it up off the larger base, so there's room to sand-scape around and under the house. Gluing the upright small pieces took forever, because I had to do a row or two and then stop to let the glue dry because otherwise I was knocking previous pieces out of alignment and getting them stuck to my arm. The angled cross braces took even longer because I had to mark and miter cut all the angles. You may be able to see some of the glue that hadn't dried yet when I took the picture--I am just so glad to be done with this process, which has taken more than 2 weeks because of glue drying and miter cutting and getting bored and wandering away!