As per my previous my post, I'm designing a couple of custom parts that I'll need to have machined.

What I have currently is a pipe, 1.5" Dia, with 4 holes in the side that nipples will be welded into perpendicularly.

What is the best way to insert said nipples into the holes in the model?

Should I draw the nipples separately and then make an assembly or is there a way I could do it in a single part drawing?