Toy excavator with moving parts.

I used 2mm aluminum tig rod as the pivots. Tooth picks or filament may also work depending on the scale. 

It will need supports on parts of the track base and at the end of the main arm, all included in the 3mf. 

Please be careful when attaching the tracks and the body together, rotate and put even pressure and it should go in well. 

A small amount of vegetable oil will help the rotation.