It is a tradition of Frank Lloyd Wright's Taliesin West architecture school (in Scottsdale, AZ) that students build their own small shelter in the desert. I am a fan of Dan Simmons' Hyperion series. If any of you read it, perhaps you remember the section where Aenea is at some strange out-of-time version of this school. Following the real-world tradition, she builds her own dwelling in the desert.
These are not necessarily cardboard box and plywood forts -- many are real engineered structures whose materials can be expensive (the students do most of the building with their own hands). I wish more architecture schools emphasized their students actually constructing some of their own work.
The students are looking for your help to support their projects, and have a Kickstarter campaign in progress.
The video below shows what they are doing:
As an aside, if you are in Phoenix, I would put Taliesin West as one of the top 2 places to tour in town, along with the Musical Instrument Museum. Phoenix of course is much more of an outdoor town. The very top thing to do in town, not just to tour, is probably to climb Camelback Mountain or Piestawa peak. Both are mountains dead in the middle of the city, something that is relatively unusual (in Denver, Portland, Seattle, etc the mountains are off to one side). The views are spectacular, and there is no funicular or cable car. The view only rewards effort.