Copper Pipe

This thing gives you the ability to create your own parts to fit with copper (plumbing) pipe. :)

For example, say you want to have a hole to receive a 1/4" copper pipe. Easy, just create a "outside fitting - boolean diff" for "1/4" and however tight a fit you want. Use that to make a hole in your model.

Or you can do a "outside fitting" and build up your model around the already drilled hole. Either way you like to work.

You can do the same for inside-fitting connections and even for both inside and outside together.