I have designed this holder because we were putting them on top of the shoe cabinet, so every time you opened it from top, the shoehorns kept falling. It does not look gorgeous, but it does the job.
It is designed for any shoehorn with at least a 6mm hole. I included a Fusion360 file in case you need to edit anything.
Best to print at 0.16mm layer height and 30% infill. The hole at the bottom is a bit wiggly for bridging, so you might need supports (I printed it without them). Best material for printability and longevity is PETG (Prusament Chalky Blue in the picture).
The author marked this model as their own original creation.