The track units are incredibly simple, in fact the hardest part I had was sourcing something for the wheels. Best thing I could come up with was a broom handle! 69p down the local shop, then chopped into 18 segments made for some useful wheels. The ends will need capping at a later date, but shouldn't be a problem.
I redesigned the sponsons for this project. The old style was basically a trapezium stuck to the side of the tank, supported by a tiny little brace. I didn't like this, so decided to scale up the Leman Russ sponsons instead. I think they look much beefier, plus it will help tie my tank into the rest of the army and give it a more "real" feel.
For the gun mounts I just used two pieces of pipe, one inside the other. The inner one was marginally longer and glued top and bottom, allowing the outer one to rotate freely. Then a quick bit of card cuttings gave me a flat panel to attach the bolters.
What I didn't do at the start, since the connect them with pipes idea didn't come to me until later, was cut holes for the pipes on the inner walls of the tank units. This would have really helped, since I could have sat them on top of the wheels to give extra strength. As it is I had to sort of guess the place to cut the whole and missed slightly. Should be strong enough, just means I'll have to be a bit more careful when changing the modular unit.