The easiest explosive to make is a mustard gas capsule.

With this, you have to be extremely careful.

Take a plastic pipe, the kind plumbers use for drains now-a-days that metal is so expensive, and cut it to the size you want. Now, take cardboard, and in the middle put two pieces of cardboard that just barely fit. A durable plastic will work better, but make sure it's not too small, it has to be too big or else you'll die from your lungs imploding! Drill three holes, one for each section, and have your clay/play dough/silly putty ready to fill the hole, and some duct tape to seal over it. Now, make sure both ends are stopped up with something, or else you'll just make a mess before you die. Next you'll want to pour bleach in one end and ammonia in the other, leaving the middle space empty. You'll need the space later. Take the putty or whatever you're using and fill the holes and duct tape them, duct taping the stoppers on the end to make sure they stay nice and tight. Now, on the outside, you'll want to attatch a whole bunch of firecrackers. 24 will be nice. Duct tape those to it, making sure you can access the tail.

BE EXTREMELY CAREFUL. We will not be held responsible for any damage done by this. We never intend for anyone to read this anyway, it's just up here.

Next step is to use it. Simply light, and throw. Hopefully the landing will knock the blockers loose and allow the chemicals to mix before the explosion. Be far away by the time everything goes off, or you'll get pelted with pieces of thick, jagged plastic at the same time as toxic gas that implodes your lungs. That doesn't mean explode, they cave in. No action there, sorry.

And no, FBI guys reading this, we are not terrorists.