Extruder Calibration Tool

Wanted a simpler way to measure and mark filament for e-step calibration on my printer. Works great for my shaky hands.

Without removing filament from the printer, feed into the groove down the center and mark at each cross groove with a Sharpee. Yields a marked filament for extrusion testing at 100, 110, 120, 130mm.

[How to calibrate](https://letsprint3d.net/how-to-calibrate-the-extruder-steps-ender-3-5-cr-10/)

Goes without saying that you should check the distances between cross-grooves to be sure your printer's x/y calibration is good. If it's wildly wrong, fix that first.