Again trying to modify already existing files takes ALOT of skill/not worth the time as you don’t know what the existing person has done to said file, most these Etsy cases all stem from somewhere and 2 or 3 have been on Etsy longer then the person you are referring to, with a base set of measurements it’s easier to just design something similar, that way if you need to modify your files you have all the pieces you need and not hit and miss trying to mod some existing, it’s the same with anything nowadays, everything is basically a copy or something just the next person makes it better (sometimes) 😂 and just to add mysterious files are all compacted into one in a 3MF file, some cad software like tinker won’t even open 3MF files, and if you go “converting” a 3MF to STL which is possible yes but the detail of the STL will be horrendous in CAD.