It's just one of those every day functions that every 3D Printer owner should be able to do as second nature.
(Select "Ungroup" then Select All, shift right click piece to un highlight invidual component, delete the rest, rotate/ settle and or slice into further pieces, save individual file, send to Print, done )
Repeat the process on the next part. I cant imagine another programme that makes it any easier than that - > "Windows 3DBuilder "
For me as a hobbist it is a laborious job that dosent spin my wheels, hence why I just generate the models. I'll get there eventually ; )