This is universal knob this can used for several purposes like home appliance mostly plastic ,machinaries better use metal 3d printing or cnc if possible.

Strength depends on infill and shell thickness shell thickness min 1mm, infill min 40%. ironing yes for asthetics

Heavy tight knobs lever i recommend 80% infill wall thickness 2mm

BORE 6mm Expension (yes) BORE LENGTH 16mm CIRCLE DIA 40MM HOLD BAR WIDTH 10MM, LENGTH 40MM

Each measurement may varies due to your slicing setting beware! Try to calibrate machine before print for better accuracy. Good luck ! If this project helps you can sponsor my next project Tip ! I would like to Share fantastic useful design. -Engineer