This is a quick and crude stand I made to see whether smaller ball joints would be adequate to hold a beat-up old yard-sale stereo microscope. I planned to use it for a work light, but the test worked well enough that I never replaced it with something nicer. Its compact and can work in cramped spaces.
The arms are about 9 and 8. The lower arm is made from a couple 3/32 x 3/4 steel straps, doubled around the ends and with a nylon spacer in the middle to help with clamping. The upper arm is a piece of 5/8 steel rod with balls at the the ends and turned down and bent to help positioning. All of the balls are 5/8 diameter, the lowest one with a 1/2-13 threaded end and a couple flats on the shank to screw into a base. The ball sockets are just countersunk holes.
From the combination of small balls and coarse threaded carriage bolt clamps it does need a wrench to set it up but then it will stay in place indefinitely, and can be repositioned without loosening anything.