I designed this excavator for the mini digger from TC_FEA. The only thing i changed on his design was the baseplate. With the new plate it is much more stable and a lot stronger. For the track i used the track design of KRUX but i designs a new wheel base to fit under the excavator frame.
40x M2 nuts and bolts for the tank tracks
44x M3 max 30mm (you will need different lengths but i just bought 30mm and cut them to the lengths i needed)
2x M8 bolt
6x M8 nuts
4x M8 spacers