replacement doorknob for shower

When the chrome layer starts to peel off, this is the thing you want to print ;)
Knob is designed for an M6 bolt&nut.
Print with the hole down on the bed and pause just before the hexagon cut out changes back to a circle. Check this in your slicer and note the height or the layer number.
If you use a bolt, you will need to print the knob at a height of bolt length -15mm or -10mm depending on the STL you use. Add a couple of mm for safety.
I use Simplify 3D to slice and one can put an object