What I noticed that was done right is that he started with a set of real forklift forks. The temper and metalurgy in real forks is important. You can't duplicate this with a a piece of 4" channel. Remember that all steel is not created equal.
Looks like a great start. I like the sliding forks arrangement. This is jult like the set I built. My set atarted out 3pt hookup, the was converted to bobtach for my FEL, and finally got modified again to also work on the 3pt Speeco hitch.
Can't wait to see your with green paint on it.