In case your oscillating sander is missing elastic oscillating bolts, these might suffice.
Printed in TPU with 60% infill.
I made this following an (potentially original) drawing someone uploaded to a woodworking forum.
This is my first attempt at freeCAD and I rarely print in TPU, but for this kind of part there seems to be a lot of leeway.
The author marked this model as their own original creation.