ok....my text got mangled so lets try again:
I finished the tank so here's a little walker for those who might be interested to do it:

Materials:lego bricks (2 2x1 eyelets(1 stud),4 identical technic pieces,)super glue,blade,plasticard,drillbitz the width of the pegs the cannons are mounted on.
I think you can guess what to do there.For the built alcove on the turret,i used a small piece of balsa cut in a roughly triangular shape,then built onto to make the 'pin' that holds the cannon in place.Make sure you have a bit of piping stciking out of the alcove so you have something to build the pin onto
Good luck converters