Leveling/measuring/comparing tool for 3D printer or other uses

I needed a way to compare one side of the z-axis level to the other side on my 3D printer as it droops when the steppers are powered off. I ordered parts to link the z-axis lead screws together however in the meantime, this tool makes it easier to compare the two sides.

**Marked "work in progress" because the bolt might need to be slightly smaller by about 0.1-0.2mm** or I printed the base with too much fill. Print with no more than 50% fill. For too tight screw, put some chapstick or other l