I don't think you would have to be a metalurgist or a materials scientist to build one, but I appreciate that it would be difficult.I appreciate the kind words, however, I'm neither a metallurgist, nor a Materials scientist. I know there are specific hand operated testing units one can purchase, they are, however, about half the cost or more of an AMP.
For now, I might just buy or build a cheap annealer (flame or induction), and buy a very cheap hardness tester. I don't want to put up a link here, but they can be had for about $125 online. I wouldn't trust them to be precise, but they would certainly be closer than my poor eyes, and they would allow me to test for repeatability across a batch of brass.