When I was chatting with Brian Holcolmb a week or two ago during his last visit, I mentioned a small project I had to cut a dado insert for my slider (which is capable of it, but I don't want to pay north of $300 for the OEM part). I have one I borrowed from another local woodworker for measuring purposes and plan on buying some aluminum stock. Brian recommended I get material a little thicker and machine both sides to insure I have accurate thickness. From that conversation, I'll interpolate that if you buy aluminum for your idea, it's going to need to be processed for thickness, not just for the shape, etc.
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The most expensive tool is the one you buy "cheaply" and often...