Many are unfamiliar with this tool or think it is just a variation on a compression tester. Both misunderstandings are unfortunate. This is an important tool, and it is actually a companion tool to, and designed to be used in conjunction with, a compression tester. If the one in this picture looks shop-made, it's because it is. I have been using this eact tool for about forty years. Find out how to build one here.

Note: The tools depicted on this page are shown for informational and encouraging purposes. They are not for sale. Sorry. I can however advise you on sourcing.