OpenSCAD code to generate embroidery hoops at any diameter. I've included 3", 5" and 7" STLs. Best if printed in PETG. You'll need an M4x35 hex socket head cap screw and 2 M4 nuts to assemble. One nut goes in the knob; one in the hoop to hold the bolt in place.
You should be able to generate any diameter hoop by changing the “inches” value. If you'd prefer metric, just change the “d” value to the diameter in millimeters.
The author marked this model as their own original creation.