The hand held I made last Spring is the best replacement for a pump sprayer you'll find. And now after using it for this much time I will not be without one. The first one I made was made of wood,..then I had one made from aluminum at the local weld shop.
It is a truly hand held spot sprayer that will hold a gallon of whatever you want to spray. When you want to spray something else,..simply switch gallon jugs. I quick rinse with water between products is very simple to do,..can be done with something as small as a water bottle. Way better than risking cross contamination and having to swish out the jug or have multiple sprayers. It uses a 3"x 4'" wheelchair or scooter battery and 12v pump. It is a pick up and carry unit with about an 18" application hose But,.you can also simply add an extension hose on the intake side and the outlet side and it will do anything any other sprayer will do,..but the other sprayers aren't a simple pick up and carry,..
There is a thread on here somewhere with a total description of assembly and design,..along with pictures.