They go by a lot of names crater maker, co2 bomb, pipe hand grenade. These are discussed in all the Co()KB0ok"S there use for this device is to kill or maim innocent people or government fat cats. But we are against shit like that. Anyways you must use good judgment when using these metal casing explosives, the shrapnel can kill you and can hit you from more than 100ft away. So be careful. Well I might as well tell you where to get co2 canisters if you may not know. You can get them at paintball store or stores that sell paintball gear. Or go to wall mart, k-mart, any mart. They are easy to get just go look.
What you need: a co2 canister full or empty, a nail or sharp object. Visco fuse at least 4inches never use white firecracker fuse. Explosive powder i.e. smokeless powder, black powder, flash powder, whistle mix, H3. and epoxy hot glue etc.
Step 1: Take the co2 canister and empty it if you have an already empty one skip this step. How to empty one is simple take the co2 and put it in a vice or in between your feet if your poor. Then take a hammer and nail, and strike the nail on the canister. Then a hole will be pierced and all the gasses will be released. Your hole should be about an 1/8in wide.
Step 2: Filling your explosive take a small funnel or a folded piece of paper. And fill your paper with explosive and put the paper facing downward the canister hole and slowly slide the powder into the hole. This may take a while. Fill with explosive about 2/3 the way full unless using smokeless powder or h3 then fill till you can't fill any more.
Step 3: Fusing your explosive most of the time when fusing a cob you put the fuse where the hole was. But now of days people tend to side fuse it. I will discuss both. Top hole fusing is simpler and safer. All you do is add your visco and hot glue around around the fuse. Sealing it off from escaping gasses. You can also use epoxy putty but that is expensive. Alright side fused this has proven to be better with slower burning explosives such as H3 and matches. You need a small nail and hammer , safely hammer a small hole in the side of the cob. Insert fuse. Or you could use a drill and drill a hole out but I advise against that. If your powder is slow burning use a bottle rocket fuse they are small so less gas escapes through the hole. And we're done.
Remember to always use EXTREME caution when lighting a cob this is what shrapnel looks like!!! SHRAPNEL