I don't always leave my Ender 3 Pro plugged in, especially during long periods of inactivity. Tomaskom here on printables made a filament guide that attaches very nicely to the frame of most ender-series printers (linked below, highly recommended if you have an Ender printer.) I took the piece from his design that attached to the frame of the printer and modified the end some so the the power cord can be hung from it when unplugged.
Recommended Print Orientation: This is largely the same as Tomaskom's. The main piece ("Cord Holder.stl") should printed with the flat top side down on the build plate, and the end piece ("Cord Holder End.stl" - designed to prevent the cord from sliding off the end) should be printed on one of it's flat sides. With these orientations I was able to print without any supports.
Assembly: The cord holder end should slot into place in the hole on the cord holder piece. It may be a little tight but should fit.
Thanks to Tomaskom for the initial attachment piece. I have printed his filament guide as well and highly recommend.
The author remixed this model.
Changed the end for use as a power cord holder rather than a filament guide.