The accidental pocket jet engine...

Step 4 Putting it together.

So first thing you'll need is to make the nozzle fit tight in to the pen barrel, my way of doing this was simply to cut the end off of the bic pen lid and fit it over the barrel and shape it so that the air holes were open, very important. after fitting it to the nozzle you slide the nozzle assembly down the pen barrel and then grip the bottom part of the nozzle and pull and wiggle the nozzle down until the air holes are at least halfway clear of the barrel bottom.