This is a quick model I designed to replace a missing foot on a padded chair from Costco. I designed it to match the original as closely as possible. It slips right on easily, and doesn't fall off. Orientation doesn't matter that much, I printed it with the open side up, but got some curling issues (it's like a 70 degree overhang), but you might print it with the open side down. Just use strong enough settings that it doesn't fall apart (I used 3 perimeters, and 2mm top and bottom shell thickness). I don't recommend printing in PLA, but you could send it and see (I printed it in Polylite ASA).
As a note, I am releasing this under a noncommercial licence but you can sell this in limited quantity on a irregular basis (for example, selling one to a friend if there chair broke). I am not OK with you using these for a business, however.
The author marked this model as their own original creation.