I had a few boards to populate and wanted something a little more steady than just tweezers but didn't want another tool that takes up a bunch of space like a linear rail system. The build consists of 3/4" ply wood, door hinges, a felt washer, a syringe and a modified aquarium pump.
The arms are 3"x10" and the hand rest is 4"x7" attached to a 3"x5" piece. I have mine mounted to a double layer of 3/4" ply mounted into a jaw horse, but you could easily mount it to a wall or bench top. The hole in the hand rest is just a little bit over sizes and the hole in the felt washer is just a bit undersized. This allows you to easily move your components up and down and rotate them. My original idea was to slide the syringe up and down to place the components but it turned out there was enough flex in the system that all it took was a little down pressure. This has worked better than I had expected!