If you want to build this yourself and don't want to get a lathe but would like to use aluminum, you can't make it from one piece. Not only because it is metal, but also because aluminum is non-ferrous and will cause cutting wheels to explode from heat buildup as they clog with melted aluminum.
You can buy discs of aluminum from mcmaster.com and stack them, or cut and sand the ends of lengths of different diameter aluminum stock, also available by the foot from mcmaster.com. You may also find a metal supermarket or something like that more local to you.
Once you have the discs laid up, you can spec out aluminum tube by the inside diameter and wall thickness (best to do while planning) to slide over and become the control section, and just cut that angle-sided pocket out with a hacksaw. Same for the projection end, cut that contour out with a hacksaw and then use a dremel with a drum sander to put the round in the corners. I'd also suggest adding a round in the the corners to the control section pocket cutout, to help fabrication.
You can use LORD brand glue to glue aluminum, or 5 minute epoxy available at any hardware store, you just want to give it some tooth by sanding the surfaces.
It's definitely doable, if you'd like to have it made, our shop can definitely handle the whole thing, or machining parts to your drawing so that you can build most of it.