Okay, I can take a hint. . . Sometimes 
This is the grain puffer, aka Chinese Corn Popper. Total internal volume, about .75 l, say 3 cups. It came with a four wick alcohol burner, and the propane backpacking stove was a bonus. Reasonable build quality, pressure gage reads in bar. There’s a heavy vinyl tube half lined with sheet aluminum, with a bag attached that’s made of nylon, or maybe polyethylene screen that catches the puffed grain.
The big Allen wrench, ummm, hex key, in the foreground is used to tighten the big screw at the top, right end in the picture, of the puffer. I keep wanting to call it a bomb, like a calorimeter. It also fits the hex hole in the latch that holds the lid closed. After 10-15 minutes of heating, the water vaporizes, the pressure rises, and when it gets to about 8 bar, you juggle the hot puffer, put it in the tube/screen bag with the hex gizmo sticking out through a hole in the vinyl, put the short leg of the hex key through the hex hole, and jerk it to open the lid. The steam explosion is both dramatic and satisfying. And relief. To make this happen, I have to hold the gage end of the puffer against my stomach, and jerk the hex key with both hands. A smaller device might make this easier, but we eat regularly, so bigger is better I plan to try less tightening of the screw, to find tight enough, but not so hard to release.
If you know how to rotate an uploaded photo, let me know. The top left is hard red wheat, puffed as-is. The smaller grains are just slightly larger than the unpuffed grain. Middle left is the same wheat with a teaspoon (maybe 5-6 ml) of water added. Bottom left is same wheat, about the same volume but weighed this time, 250 grams, with 10%, 25g of added water. This makes a reasonable snack or cereal. Well, they all do, but the first two may burn more calories chewing than they contain. Top right, white rice. Bottom right, 250g rice, 25g water, then puffed. I waited, a couple of hours minimum, to let the grain absorb the water.
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