A better calibration print

I'm not happy with calibration cubes. 20mm is not enough to find any real inaccuracy in 3D printers and at such small sizes filament contraction is a significant contribution to any error you find. 3D printers naturally have jutted-out corners where the dwell time of the nozzle overextrudes. The bottom layer is normally smashed down a little and top layers tend to jut out a bit as well, leaving impossible to measure surfaces.

This calibration plate features:

Rounded corners!
- Easy to measure with calipers

Inner diameters!
- Measure filament contraction and the infamous ID filament drag! Make an excel sheet with your measured %errors to make perfect ID's!

Vertical bores!
- These are small so you won't need supports!

Large footprint!
- Test bed leveling and precision all at once. Easily measure skew!