Moped Army

So here's what I did: drilled 6 holes, 1 every 60 degrees, and made them through all layers, steel, aluminum, steel.



I tapped the holes and then put in these M8 set screws so that they protruded the ID by a mm or so, then turned them down flush.



I made the two rings such that I had to press the steel into the aluminum with considerable force using a table vice (and also coated the joining surface with JB Weld, just for kicks), so it's probably not necessary that the screws penetrate the steel ring, but it can't hurt.