[Ianworld]

Well the thing to understand about cutting out holes in your large aluminum extrusions to understand what your team is capable of. The last two years my team has just taken a 3" or 3.5" hole saw to 4 x 2 aluminum extrusions. That works pretty well. If you have access to a mill and a lot of time you can use something like what you have above. As for the material you leave i guess it depends on what size extrusions you're using. I like to leave enough material that i could drill a hole in it and bolt to it.