CalibrationCube for flowrate calibration

I had major problems with the print quality when it comes to infills, or sharp perimeter turns. The infills were printed bumpy, and my nozzle plowed through or rattled over them. Furthermore, the second extruder's nozzle bumped also against the print when it crossed the infills.

The guys at Maker's Tool Works said that I have a flow rate issue most likely, i.e., my flow rate is too high. It has surprised me since I calibrated my extruder as Thomas Sanladerer explained at YouTube (https://www.youtube.com/watch?v=YUPfBJz3I6Y) and got a nearly perfect result.

But after reading the article at

http://ohmeye.com/2013/reprap-extrusion-flow-calibration/

I reduce my flowrate from a value of 105 to 98 (about 7%) for my current filament spool. The results are astonishing. No bumps, no crashes, no plowing.

So I build myself these two calibration cubes that help me to figure out the right flowrate after a filament change. These models don't take long to print, but you have en