Here's Rev B on the sprayer I built. Upgrades include larger tank(35 gallon), better spray gun, onboard pump storage, and 12V solenoid valves. The tricky part was trying to figure out a way to power the switches, and keeping it easy to mount. Ended up using a "bell box" mounted on a single 9/16 carraige bolt thru a previous hole in the fender. The power comes from a pigtail to a 12V power outlet.