sands uneven edges on wood and keeps natural formations, just smooths them out
good for sanding large quantities, just need to make a tool path

this uses belt sander belts cut up, it needs to be fabric backed

fold about 5mm of the belt back with the grit inside the fold, it should slide into the slots. you may need to sand the head a little

using a metal ruler helps to get the belt out

uses the shaft from bits like the one pictured ( i made this a while ago and cant remember exact dimensions, you could also make one yourself if you have a lathe)

the recess holds the nut for the shaft, if you have the tool spinning the right way it tightens automatically so hand tight works perfectly fine

measure the diameter from half the sandpaper to half the sand paper on the opposite side (see badly drawn pic)

set the bit as an endmill

start the toolpath away from the workpiece and move in on a radius, so one pass at full depth

you may need to do more passes depending on material, sandpaper and rpm

when you cut the belt into strips, make sure the tool path goes around one strip below the work piece. it doesn't have to be super accurate since its flexible

limit the rpm to around 3000, it sands steadily and when bits fly out, they dont carry enough energy to do any damage. i tested up to 5000 with success but its a bit unnerving

it works fine with a dust extractor, it just needs a solid base instead of brushes

i uploaded the stp file so modify to whatever you need