I didn't spent much in materials for this models, but I preferred to invest more in rigging it. It can be animated with one central control that have sliders and spinners to:
- rotate the entire vehicle (tracks will automatically and oppositely spin - rotate the top of the vehicle - extend arm a - extend arm b - spin the tracks simultaneously (to travel) - bucket open and close
-pipes will bend accordingly to the arms -tracks will move automatically and in opposite one to the other when the excavator rotate (like a real tank)
Link the main control to a path and everything will follow correctly, model is centered in 0,0,0
Use state scene to switch between scene presentation with white background or lighting with sun (and other settings faster for animation).
Download the preview animation (best results can be achieved)