Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4166380.

I wanted this sander but didn't want to pay $6 for the actual sander part so I just purchased the belts and modeled this around these:

https://www.amazon.com/dp/B01IRLEALI/ref=cm_sw_em_r_mt_dp_U_uHvsEbQ2TMASE

Using those yellow 3D printer bed springs:

https://www.amazon.com/dp/B07SCYM119/ref=cm_sw_em_r_mt_dp_U_9OvsEb1H3GHA7

If you'd like to print these separately to fit on a smaller bed in Simplify 3D go to Mesh > Separate Connected Meshes.