I built this sprayer in 2002 (I think) out of 2" square tubing that I bought to build a squat rack. I still plan to do the squat rack some day! I did this before I had a Miller 210 and a 7x12 band saw. I cut almost every piece with a hacksaw!!! The welder I had back then was a Clarke 100e wire welder w/gas. The frame was pretty easy (if you like hacksawing) and all went together pretty good. I designed it as I went along. The boom section is 16 feet wide. I made the boom out of the same 2" tubing as the rest of the frame. Looking back I wish I used something smaller since the teejet valve bodies have hangers but not for 2" tube. I had to make my own hangers. Each of the three boom sections has 4 spray nozzles. The nozzels are tee-jets with with check-valve bodies. They are controlled with a selector valve that allows any combination of the boom sections. There is a pressure relief valve to control the spray pressure. I used a glycerin filled gauge on the selector valve. The pump is a 4 roller Hypro that I put cam-lock couplers on. There is an 80 mesh filter before the pump. I made the tank from a 55 gallon HDPE drum. I cut the top off of a hand pump style sprayer bottle and used it for a sort of funnel that I plastic welded to the bottom. This allows every bit of solution to drain completely from the tank. The plastic welder was a Laramy that I borrowed from work but it didn't work very good because someone lost all the tips except for the one used for joining flat plates. A ready made tank would have been nicer but they are very expensive. I painted the frame with red Rustoleum. I plan to add hydraulics to fold out the booms when I get some time. I never kept track of how much money it cost to build but I'd guess I have around $500 in it.
Interesting story about the gauge... When I first tested this unit I ran the pressure low and slowly increased it. I was looking back at the pump when bang! Something exploded! I thought a hose came off. Something hit me in the side of the face. The pressure gauge which was level with my head had blew out the glass. The glass and the glycerin were all over my face. I only opened one eye since I could feel glycerin over the other. I looked down and blood was dripping into my hand. I thought wow, I must be pretty bad. I shut off the tractor and walked to the house. I stopped in the garage and decided to look in the car mirror so I could tell how my wife would react. I had only one time little cut on my nose! The glycerin had made it seem like I was bleeding much more and with the pain of the impact I thought I had serious damage! Got lucky! The gauge exploded because I neglected to remove the tiny little plug tip on the top that you are supposed to cut off. I installed the gauge several months before testing and figured I'd cut it later in case I had to tip the unit over.
Anyway... The thing really works great and has an excellent spray pattern. This weekend I added a hand spray wand and a couple of little mods I wanted to do for a while so I took some pics.