I've been thinking about making a boom to go on my four wheeler to spray some hard to get to small plots. Has anybody made one? I have a good idea on how to make it just struggling on how to attach it.
Have you looked at the wet booms made by fimco? It attaches to the bottom of the spray tank and fits within the width of the 4 wheeler. it will cover a ~30' wide swath and you can turn off either side or the center with it. You can also turn the end nozzles to spray up for killing brush.
I built one with pvc backbone that can be mounted on an atv or side by side. Those wide fan nozzles are great for glyphosate but if you are spraying chemicals that require precise amounts, it's more difficult. Mine is 6ft wide and I can follow my tire tracks pretty well. Seems to work pretty well so far.