Assuming you can source incandescent lightbulbs of various wattages; a dim bulb tester is the simplest piece of test gear to make...All you need is an extension cord you don't care about and a lamp socket and some incandescent bulbs that is it. The extension cord has 2 wire that run from end to end. Cut one of the two wires and connect the ends on either side of the cut to the 2 terminals of the lamp socket and add your light bulb.....So easy a cave-infant could do it!
