This is a 20 mmx 20mm x 20mm calibration test that I personally found useful, to quickly test parameters in my slicer. The texts have been extruded at different lengths (mm) as follows :
Top Text: T=-1, O=-0.5, P=-0.5, ___=-1
Back text: B=1, A=0.5, C=-0.5, K=-1
Bottom Text: T=-0.2, E=-0.25, X=-0.3, T=-0.5