Few people on here use ally profile & there are a number of different systems about. as for fitting the rail supports then yes people would drill & tap themselves but it's not difficult if you take your time & use clamps rather than try & hold stuff by hand.
Have a look at this thread, very interesting I thought but then I know nothing about pick & place machines lol. Might give you some ideas for your own design.

http://www.mycncuk.com/forums/other-...ace-build.html

I would take a bit of time & make sure you get the design sorted before you start to purchase anything as builds have a habit of changing a lot from the original plans.