With a friend, Richard McMichael, it took two weekends to build the observatory. First we leveled the ground and put down pavers, then built the trusses and cut them at about five foot from the ground. Next we framed the lower part of the observatory and put two barn door rail supports made from 16' 4"x4" wood beams horizontally along the top of the sawn off trusses. The end of the 4" x4" beam that was free was supported by vertical 4"x4" on pier blocks. The pier blocks had vertical screw adjustment making it easy to level the barn door rail supports. Then the barn door rail itself was screwed down to the supports.

The remains of the roof trusses then had the wheels that fitted into the bar door rail attached, and the truss/wheel assembly slid into position on the rail. The roof was then framed out, and since it was constructed on the wheels, it was able to move back and forth on its wheels inside the rails. Lithium grease was liberally applied to make the whole roof slide easily and quietly. 

An additional benefit from using the barn door rails was that because they are designed to hang doors from them, they have a lip that stops the wheels from being lifted out. This means that I don't have to worry about the wind lifting my roof off, unlike some designs that use rails.

Holes were cut in the wooden floor for the legs of the telescope so that even with people walking around inside the observatory the telescope doesn’t shake.