I have seen many interesting DIY microscope hacks in hackaday and eventually I needed to make one too. Sometimes inspecting PCBs for shorts or trying to read faded IC markings actually requires a microscope, but I don't have one. So, I made myself the next best thing - an addon(can it be called addon? Probably) for my cheep Motorola E smartphone.

As for the building process - there is not much to it:

Take an appropriate sized plastic sheet. I got mine from scraps I had lying around. I don't know what this plastic is actually called, but I know it is used to make like signs for commercials and whatnot. Cut it out in size and shape needed for your phone. Use dremmel to cut out hole for lense and side buttons (if any). Use hot-air gun to bend it in the shape. Glue in the lens you got from and old scanner and you'r done! Clip on the lens and start checking you'r PCBs.