This is a simple tool setter that I just finished up. It consists of two machined parts and a small dial indicator. The first part was made from a small piece of 3/8 dia. aluminum. It is bored to provide a slip fit over the stem of the indicator. The block that holds the indicator is bored for a snug fit so that the indicator can be removed if it is needed for other duties.
What the tool does is to allow one the ability to change tools and set them to the same zero in the Z axis. An example would be as follows: Set a 3/8 endmill to zero on the tool and set the mill's dial or DRO to zero. Mill the top of a piece of stock. Next do the same with a spotting drill and spot a hole. Next repeat with a drill (Zero on the tool setter and set the mill's dial or DRO to zero). Since the drill is set for the same zero as the endmill, it is possible to drill to the correct depth.
-Bob