To use this, print out a set.... Yes I realize that if you can print this thing then you must have your printer set already and would not need the thing... but still, you might need to re-set it someday!

Set it on your printer table, slide the short end under your extruder head, but stay behind the raised line, this will make sure it pivots and will not crash the head. Over-Travel will simply raise the end of the lever above the reference (much better than crashing into the glass, and scratching the PET tape) when the lever is even with the reference, the head is the height of the reference. I made mine 19mm, so I could also use it to set the bits on my cnc mill and cnc router which are both in inches... 19mm is 0.748" so close enough to call it 3/4". I've included a slic3r 0.97 .ini file that I used to slice it with, it could probably be a little better, but I got acceptable results with this. Since the parts are so small I have to run them slow enough so previous layers have a chance to cool, otherwise it gets kind of melted looking.