Snug Hugger

You can make a different sole part by outlining your foot instead of using the model part here or resize this sole part in modeling software before printing. After printing, the model can be cut with scissors to fit your slipper or similar shaped shoe.

I printed the models shown in the photograph with a 0.6 nozzle on a CR-10 mini printer.

Top and bottom layers should be reduced to 1 in your slicer. With a 0.4 nozzle, you will have a more pliable print if you decrease the z-height of the model to 0.4.