Take some measurements with a calliper. I don’t know if rubber hose can be had in that small a size, but if it can, rubber hose slipped over and glued to the axles might work.
@joshc if you can get the exact size you need you can stretch tubing by heating it up (helpful if inner circle is too small.
failing that In the past ive also used a 3D printer to print flexible filament like TPU, its worked well for me in the past fwiw