We used as many natural, unprocessed, and re-used materials as possible, which made it less expensive but much more time consuming than buying everything from the lumber yard.
Step 1: Preparing the frame
So we moved right on to priming with a rusty metal primer, and then a coat or two of quality metal paint.
Step 2: The floor
As we live near an old steam powered sawmill, we decided to use rough milled redwood 1x6's for the floor, so we ran them through the planner and then the edger to get a beautiful floor. As we were using true one inch thick boards we decided to screw them in with appropriate length screws from the underside so that no fasteners would be visible. To protect it for the rest of the project we covered it with some 1/8 inch plywood pieces we had laying around.