Hello in Holland.
I'm also new to WRA2 Fourm and like you started by looking for away to entertain the kids. However Dad's has the most fun, hidden away in my workshop until all hours.
As for the Gardena bottle cap connectors. Air command Rockets has a great tutorial on making them ( the rocket gods )
http://www.aircommandrockets.com/constr ... htm#Nozzle
I was feeling lazy when I watched this and decided to just crank the gardena nossle straight on to the bottle as it is out of the box.
It works great and I've hydrostaticly tested them to over 120psi.
First, I use Teflon tape on the bottle threads, then crank on the classic plastic gardena nossle with a pair of vise grips, becareful not to twist the bottle out of shape. Then wrap the point of connection between the nossle and the throat of the bottle with pipe wrap.
Its a special tape good to 100-150psi. It's not sticky, but as you wrap the tape over itself the pressure and a chemical reacation creates a firm seal.
They seem to work great.
