This is an alternate trolley solution for a ceiling mounted Unistrut bike storage system. You can follow the guide here for assembly instructions and full parts list.

You'll need to print out 4 axels and 1 trolley for each complete unit. I printed these in PETG (60% infill, gyroid)for durability and printed all parts horizontally on the bed so that the layer lines are perpendicular to Normal force with minimal supports on the axels. Everything press fits together but you can add CA glue to make sure the axels don't work themselves out.