needed something to hold the endmills for my new milling machine an instead of just downloading something someone else already had made i deicded to just make my own so i knew it would work with what i had on hand. the little cases the endmills come in are 13mm square that way u can make sure they will fit b4 printing. they are alittle snug when pulling them out but id rather them have a snug fit than be wobbly in the stand so u could scale it up by 1% if u wanted a looser fit or u might be able to clean the print up some with a deburing tool an help loose the fit, i just printed it pulled it off the printer an attached it to the wall an put the endmills in it so no post processing. the endmills i have in it are all smaller endmills 1mm up to a 8mm so i dont know what the biggest endmill that it can fit is yet ive just gotten into this so as of right now im very new an only have experience with what i have on hand, never got to use anything like this b4 i got one so for those that know alot more about this stuff might already know what sizes will fit and will not but as soon as i get ahold of something that is to big to fit this holder i will make a new one that will be for the next size up i guess, but until this this one will do the job.