A die grinder is a fairly blunt instrument, not something you'd want to (or even be able to) use for putting switch/button holes in aluminum.
The die grinder is the exacto knife of the steel shaping world. And it is used for porting aluminum engines to improve air flow, which involves shaping things smoothly and precisely. It would absolutely do stuff like this, using a carbide burr. They make burrs specifically for aluminum, as well. You'll have to finish the corners with a file, obviously. This is for the rough shaping.
don't you want a safety switch with 1/4 inch? I kind of feel like using a router free hand for metal is dangerous even if its overbuilt because of ergonomics. They are like a giant can
Well, a stubby die grinder isn't much different. It's always dangerous, and I suggest full face shield whenever using a burr in metal, cuz chips in your eye.
https://www.amazon.com/Metabo-GE710-Compact-Variable-710-watt/dp/B00FDLB9OC/ref=sr_1_8?keywords=metabo+die+grinder&qid=1571332977&sr=8-8The problem with electric die grinders is they are expensive. There are cheap imports in the realm of the 25-30 dollar trim router, but they are junk with unbalanced motors.
I have an even older Dremel, maybe 25 years or so. I have a fantasy of using a Dremel-like tool for routing in 1.5 mm aluminum -- is that reasonable?
Dunno. I've routed up to 5mm aluminum using trim router with an endmill, in a router table. That works good, but it's really slow, because you have to take shallow passes. IIRC, I was taking max 1/32"- 1/16th" cuts (but my router table has some compromises to the rigidity). This is one of the reasons I built a threaded incrementing fence, to make that find of adjustment quickly, and even down to 1/64th" for final pass. 1.5mm might be doable by a Dremel, but if you are imagining doing this free-hand, I suggest you stick with burrs.
*edit: You can cut aluminum with any bit for wood. But if you route plexiglass or aluminum with a straight carbide cutter for wood, it doesn't cut as smoothly and it also leaves weird diagonal lines on the edge. Likewise, any drill bit or saw for wood will also cut aluminum. Even large forstner bits in a drill press; you just have to drill a pilot hole for the point, although some peeps just press a lot harder, lol. I use the router table on aluminum mostly for finishing and dimensioning, slots/grooves, and partial cavities. It's a lot like manual milling, but upside down. And with stop blocks instead of crank knobs; and you might have to include extra material for indexing against the table/fence which will be cut away when it's done. If you need tight tolerances, and esp parallel edges, a router table can get you there, eventually, you just have to want it bad enough, and you might have to add some parts along the way. Adjusting the Z-axis is the biggest pain, left on my table. I have a couple ideas on how to amend this, but I haven't had the need, yet.