Our daughter turned 3 in the spring and we decided she needed her own playhouse. I started out scouring craigslist looking for a used playhouse at a fair price but the cheap ones were gone before I got to them or people were asking way too much for a used playhouse. We decided to build our own. We thought it would be cheaper to build from scratch rather than buy a pre-fab kit, we were wrong. The upside was I got to design it and our daughter ended up with unique playhouse just for her! It is made out of cedar except for the four corner posts that are pressure treated. After adding the cedar shakes to the exterior we installed thin plywood to the interior walls to hide all the nails protruding through. The roof is made out of corrugated metal.
Of course every playhouse should have its own mailbox.