Air Powered Motor (Q45000)

As a kid I had a an air powered toy car. Yesterday I got the idea to try and design an air powered motor which can later be incorporated in all kinds of applications. I'm not going to explain the principle as the animated GIF in this link explains it perfectly: http://www.animatedengines.com/co2.shtml As I have only completed my design work today I haven't yet had a chance to print it and look for any flaws. Also for the sake of easily printing all the parts the design might be slightly over complicated. It is however fairly small (6.28cc capacity) and therefore all parts "should" print straight and square. One major feature of my design is that multiple motors can be daisy-chained to form a larger multi-cylinder motor. So far the only thing missing is a 3mm wrist-pin connecting the piston to the con-rod. As this is a work in progress I do not know what the clearances are and therefore how freely this will turn once assembled