Make: Magazine Vol. 05 has instructions for building a pulse-jet in a mason jar. This is version 0.1 where I'm testing doing some building of the diffusion cone and other bits differently.
In this version the diffusion cone and the lid are just regular aluminum foil used in the kitchen, or making hats to block cosmic rays and various alien transmissions so the voices will stop. Make them stop!
The aluminum in the cone burned and ripped and the lid hole met with some damage too, but I was able to modify their shape and orientation between ignition attempts to find what would work.