this is a widely applicable two-part doorknob design.

simply place the doorknob through the hole in the door, push the nut through from the other side - and you're set!
(some super glue recommended if hole size is bigger then 16 mm)

Creality

Ender-3 V3 SE

No

Yes

.4 mm

10%

print time for me was around 1:15-1:30 hrs per doorknob set.

near-to-none post processing. just remove the supports and you're set to go.

this has been originally designed to replace keyholes for a metal Ikea cabinet (specifically the one in picture below), which otherwise did not have any handles.

all i had to do was simply remove the keyholes (which were held with one nut only), design the doorknob on onshape to fit exactly the same hole size, print, and pop it in place!