A fire tornado that works without external power and can even burn inside (for short periods of time of course, be safe). There are videos included at the end of the project.

As with any project involving fire, have a plan mapped out in case something goes wrong, in this case a fire extinguisher or some water or a fire blanket, etc.

This works because as the flame burns it pulls air in from the bottom and in doing so imparts some angular momentum. this causes a vortex to develop in the cylinder pulling the fire up with it.

Supplies

3D printer (to print attached STL), candle shade (Glass Candle Holder Shade | Hobby Lobby | 2172344), concrete, V8 can (or similar), patience, a fuel to burn (Isopropanol works but has a bit of water in it that fogs up the glass, ethyl alcohol like Everclear burns quite nice, gel fuels should work as well but hasn't been tested yet).

Fire Tornado for Pop Can.stl
Download View in 3D

Step 1: Print the Base

The attached STL should be printed on a 3D printer. This was done in PETG as it holds up to heat a bit better. I switched colors to make it look a bit nicer as well.

Step 2:

Mix up some cement and fill the base around the can. I initially used a pop can, but the diameter was a bit too large in my reckoning so I switched to a V8 can. I had cut it short before putting it in the cement. If done again I would want to cut it until afterwards. regardless taping it down so that it won't 'float' out helps a lot. After the cement is dry (and the can is cut) bend over the edges to remove any sharp points.

Step 3: Finish Assembly

Make sure that the glass fits well. This shows the edges bent over as well.

Step 4: Test and Enjoy

Put some fuel in the can, start with only 1/4" or so the first time, for me this lased 5 minutes or so. The fist image shows without the glass cylinder. The cylinder recommended shouldn't get too hot that it can't be lifted up to snuff the fire, or simply put a cap (nonflammable of course) on the top and the flame will die out after a few seconds.