Posting because it really helped. Got pretty far cutting out blades with angle grinder wheels etc. but when fine tuning with the Dremel, it took forever. Found this DeWalt battery powered die
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DEWALT XR 20V Lithium-Ion Cordless Rotary Drywall Cut-Out Tool (Tool Only) DCE555B - The Home Depot
I'm a Milwaukee and Bosch guy, but IMO the DeWalt oscillating tool takes the cake for ergonomics and control. : r/Tools