I used to be pedantic and needed sizes and specs to confirm my design before manufacture. Experience will tell that you to use what you have to do the job. The bolts could be a larger dia, the rails whatever size you have, in plastic, metal or wood. Bob's is a good copy with what he knows are improvements. Collect a few pictures of the beast and have a go. If it works well, great, if not make adjustments to the design. I use solid bars rather than studding. My "wheels" are 1 piece, etc. Go for it. My major mistake was to make things too big and chunky. So strong enough.