I'm currently building several walking robots, all powered by servos. The problem then arises in working out the extent of motion with each one and also the range of motion available. I have several dumb testers, but needed one that displayed the actual arduino servo position number, from 1-180. This means I can manually adjust and take down the values. An arduino, 3 pots, some pins an SPI OLED and a JST is required along with a cheap power converter to ensure that it all runs at 5v.
I initially started out with a plain box, but then thought "What would Adam Savage do?" and so added some design details, sprayed it in primer and with various inks and weathering powders gave it a used look.
I also made some nicks and cuts and painted them silver to give the impression of a metal box and painted and dirtied up the knobs. A glass cabochon was used as screen bezel.
code available : https://www.instructables.com/id/Arduino-Triple-Servo-Tester/