This is a small modle rocket engine. Tips- Print it 100% infill (or it may melt), use raft supports, press it with any solid rocket fuel ( I used 70% potassium nitrate and 50% sugar). Insert it into any modle rocket with a similar diameter or just fix to a stick and you are ready to blast of! 

( Note that my tests had showed that several ajustments to the weight and nosel diameter are needed)