Hi Martin, usually in MoI you want to use Booleans more as a primary way to actually construct the model..

Some things like rounding tends to work easiest when there is an edge in the place you want to do the rounding - by doing the Boolean to combine the objects together they get intersected and get an edge formed there, then you can select that edge for filleting...

That's normal to build some pieces as separate objects to start with, but you don't necessarily need to hesitate to boolean things together until later, particularly when you want to do some filleting which will depend on pieces being combined together.

- Michael