I wanted to make an outdoor play space for our kids.  We don't have a sprawling lawn, in fact our backyard is a eucalyptus grove, and hilly.  Inspired by the architecture of some of the houses around us in the canyon, I came up with the idea of a German style A-Frame. It needed to be water tight, and we needed to keep the wildlife out so I decided to make the roof out of green house corrugated sheets, alternating clear and opaque.  I had to dust off my math skills, and of course get some help constructing it from someone who knew how to build structures (Ben Jennings), but it turned out to be a 4 hour project and well worth the money $285 (comparable kits out there are upwards of $1000). When we thought about it, if you doubled it in size adults could actually sleep in it. We added a hanging chair to one of the adjacent trees, and have grand plans of putting an old playground slide into the hill and maybe even a covered sandbox. For now we have a space for the kids to hide, swing and do their thing.