Welcome.

Get the plans drawn and up for us to pull to pieces. . Er mean advise upon. .Lol

Good choice to ditch MDF idea it's only any good for spoil boards and throwing at the dog when it shit's on path..

If your thinking to cut aluminium then it will need to be built much stronger than you would a purely wood/plastic working machine and you'll need a much better spindle than a basic router can handle so be prepared to spend more money. Routers bearings don't handle the heat and forces cutting aluminium creates and will die quickly if doing lots of it or long jobs.

Post your ideas and ask the questions you think are dumb and between us we'll help you'll build a great machine.