We are working on one right now. It is an old doghouse that our Dobermans used and it measures 4x4x4. It needs some revamping but it still has the frame and the little door so we thought it may not be too much work. (yeah, right!) The roof is only a slant roof so we need to extend an awning out over the front to help with the weather and of course, we have to add on the pen. Wish I had photos but we are barely started on it so those are yet to come.
Good luck!