This modern playhouse is an easy DIY project using 16mm pine plywood or OSB (oriented strand board), both of which are affordable board materials that can be placed outdoors after being treated with a suitable exterior sealer or varnish.
Recycled tire seat for outdoor classroom. Treated plywood, 2 inch foam, clear vinyl then covered with outdoor fabric. All stapled underneath. Screwed 3 little "legs" to bottom of plywood that sit down in the tire like a plug of sorts. This keeps the seat top in place. Stinking adorable!