I love the original idea and project of airwayman1. However the original knobs on the handle seemed to me to requier modificatio - they were too loose. So I modified them a bit, that is lengthened them, and added two holes. Now you can assemble the two knobs and secure them by pushing a filament thread through the holes. Finally, you can use a lighter to melt the filament a little, securing it against falling out.

For vertical printing.