I thought the exact same thing as you. So during a trip to the cabin, I made one from a coffee can, a can opener on a Swiss Army knife, a bent coat hanger, and a stick for a handle.
It took considerably more than three minutes, and my first attempt did not work nearly as well (I didn’t get the ventilation holes big enough.) The coffee can was also a bit short and wide. It lasted several years, but the metal eventually failed due to the heat.
I like my purchased one a whole lot better.
