Filament spool rollers - also for Eibos Easdry drybox

I had intermittent problems with underextrusion from filament spools scraping on the bottom of my drybox, so I quickly bashed together these little spool holders. They can be used either inside the dryer or on their own. I used some crappy 4x13x6mm V-groove ball bearings I had left over from my 3D printer; you can easily find them under "V-groove bearings" on Aliexpress for pretty cheap. The U-groove version should work even better. Careful, the (much better quality) extruder idler bearings won't work since the groove is too narrow for the rim of most filement spools. For the hardware, I used 14mm countersunk M4 screws I had lying around.