I don't usually offer trade secrets in public, but as to the 400 degrees for the powder, please note this:
With all those welds (very pretty welds I might add :-D), it would be a REALLY good idea to wire brush all of them and then outgas the cart at 500 degrees for a few hours before they start the blasting and prep work. It'll diminish/remove any trapped air and impurities in the metal and keep it from blowing out through your powder.
You can also buy all-metal casters that will survive the curing heat and won't leach grease all over the oven.
I can't wait to see what color(s) it's going to be!
