Importing STL/3D Files of Miniatures and Items

I 3d print my minis for my home games and have subscriptions that have allowed me to acquire hundreds of STL files that I would love to be able to drop into a map to liven up scenes. I see you can a selection of NPCs we can use but it would be amazing to be able to drop in 3d versions of the minis we've used on our tabletop for over a year.