Mills and others

I wouldn't say that the HF mini mill is a piece of junk. It is what it is. It's meant for doing very small work. I believe that if you tried to make a chassis on that thing, you'd find that you were better off making one by hand. The one that you linked to can only make very small and shallow cuts and lord help you if you are working with 7075, rather than 6061. The mill that is one size up is OK. I don't know about making a chassis on it. It might still be too small.

If all you are going to make is flat parts, you might also want to consider something like a 2x2 router, but of course, we're talking way more than $300.

I lost my mill in Katrina, so I'm just using a rather large drill press that I put an X-Y table on, but my drill press allows the use of an end mill holder because it has an MT2 spindle. I've been making my motor mounts on it, but I wouldn't even attempt a chassis.