Completely self-built except for the window frames, which were bought in. Fully insulated and contains the most comprehensive selection of aviation memorabilia (including a couple of unique items) you can pack into 2m x 3m. It's a 'work in progress' and eventually will be lit by a 12v solar rechargeable system using aircraft lights.
This is basically 3x3 and 4x4 fence posts concreted into the ground under decking then clad with T&G. The window frames come from windows4sheds. I never drew up any plans for this, just put the main posts in the ground then replaced the decking and built it from the ground up.