We have lost the original clamp foots, so I've designed these for better wheel stability on the table.
Print with the wider side on the bed. Cut a piece of rubber circle and glue it on the bottom side for better adhesion.
Use stronger force to fit it on the clamp - it fits tight intentionally. You might try to fit it using a slight angle and then it will click inside (or break apart if you are unlucky).
I have used PETG, but other materials might be ok, too.
The author hasn't provided the model origin yet.