I designed this presser foot for freehand sewing (with the feed dog disengaged). The circular profile allows the material to feed smoothly from all sides. The key to using it is to remove almost all the pressure on the presser foot - I do this using rubber bands.
Printed in PLA with 0.2mm layers (finer may be better). You'll want to lightly sand the underside of the foot so the fabric glides smoothly. You'll also need a 1/16" dia, 5/8" long steel pin.
To lighten the pressure of the foot, I use four #33 rubber bands - two sets of two in parallel and then loop the two pairs together to increase the length. I then just hooked the open ends together with a paperclip. Loop the rubber bands around the business end of the sewing machine and underneath the edge of the foot mechanism as shown. You can increase or decrease the tension on the foot by shifting where the rubber bands contact the body of the machine. You want equal tension on the front and back and just enough tension overall so that the foot just barely presses against the fabric.