OT, but only slightly....
When I was 12 or 13 ('57 or '58,) I had a girlfriend whose dad had a homemade carbide cannon. I watched real careful when he had it out, and went home and made one of my own. Even though I was in a real no-gun household (only women and me, as my dad died in WWII,) I somehow sneaked this one past the censors.
Take an old-time (heavy-gauge) quart paint can and clean it up as necessary so the top fits snug. Bore a hole (I used a big nail) in the top towards one edge, and a finishing-nail-sized hole in the center of the bottom. Get a chunk of 2X4 long enough to contain the can, and gouge a can-sized groove in it from the middle, slanting deeper to the front edge.
Mount the can (SEAM SIDE DOWN) on the 2X4 base, put some wood screws in the sides of the base and wire the can down by using baling wire (which I got from the newspaper bales on my paper route,) and tighten the wire by using a screwdriver as a turnbuckle until everything is tight. Attach a length of screen-door chain from one of the screws to the lid using a machine screw and a lock-washer nut combination. About 3 feet should be enough - that way (a.) you don't have to chase the lid, and (b) it won't come whipping back and smack you when the cannon goes off. Guess how I learned that.
I lived in coal mining country, and in those days the miners still used carbide headlamps on their helmets. The local pawnshop sold cans of Calcium Carbide in gravel-sized lumps for cheap, and here we go. Put about 20 rocks of carbide in the cannon, put your thumb over the hole in the bottom, and spit on the carbide. Tamp the lid down tight, and set the cannon on its base, still holding your thumb over the hole with your hand on the top of the cannon.
Strike a kitchen match, remove your thumb and hold the match under the center hole. BLAM! I've had Big Bang cannons, and believe me this thing will make 'em sound like cap guns. Imagine a 12-gauge going off at arm's length, pointed directly to the side.
And no, we didn't use hearing protection, and yes, my left ear still goes blank every now and again over 50 years later. And for God's sake, don't tell your mother where you got the information.