Z-axis Position and Level Indicator for Monoprice Maker Select / Wanhao Duplicator i3

Every once in a while, my x-axis rods go askew. I wanted a quick indicator to tell me when I needed to re-level it. This is the result.

This is designed for the Monoprice Maker Select, but should work for the Wanhao Duplicator i3.

Mount these on the bottom of the x-axis rod carriage, as shown in the photos. You'll need a little glue.

I used some printed rulers to give an indication of height. I don't know if the resolution is sufficient to tell when that axis isn't level, but I have a g