Take a tin can, take an airbag inflator w/ sodium azide in it for the shock-sensitive primary explosive and either Guanidinium nitrate w/ an oxidizer (like copper nitrate) or Ammonium nitrate to surround it in to act as the secondary explosive (optionally you could instead use a mixture of potassium nitrate and silicon dioxide to send hot particles flying everywhere to make the reaction retain heat. Then just add a wooden dowel from a broom handle for the grip, and after that's all attached, drop it from a height and watch it explode as it lands on the bottom (you could add some kind of weight to it optionally). Also, I've experimented with the idea of using compressed helium or argon-helium mixtures for the explossive as opposed to a chemical explosive propellant that you can put in a gun. You could possibly wire a car's airbag alarm sensor as a detonator for a bomb as opposed to an impact-activated grenade and make it remotely detonated for you to activate it.
R8 my weapons.