Bought a whole bunch of 6061 3/8 aluminum plate on ebay a while back and I just got in my order of 3in round bar a couple days ago. I milled out one piece of the plate yesterday but it ended up being wrong. I've made 3 new pieces today. My mill skills still arent the best but they are improving I think. These will be constructed exactly like the steel ones I made before. BUT, I will be adding to the wall thickness and keeping everything at 3/8 including the round stock that actually clamps the forks. I hope to get 2-3 sets done by TF. My one welder took a dump though, to the tune of a $600 control board that might not even fix it. So I'm left with the 1970's vintage Miller Dialarc that does good on aluminum when it wants to and can ruin a piece otherwise. Its just weird like that.
One of the downfalls on the old steel ones were that where the handlebar anti-vibe bar mounts went in was not tapered correctly. This made a poor fitment and allowed alot of movement in there that I didn't particularly care for. I talked to Ronnie and he made me a couple weld in inserts that had the exact taper required made out of 6061 Aluminum that will work great.
I've got to order a few more pieces of stock, and then get cracking on turning out the round stock that'll actually clamp the forks. I think these will be very cool when I get done and they will definetly be tough. I plan on beveling all the weld surfaces where I can really stack the weld up and make sure everything is hooked together well. I also am figuring on making a "test" top and bottom plate and put them in our hydraulic press for a break test. See just exactly how many lbs of force it takes and where they fail at.