Economy Class Tank

This is a working tank model which can be used as a platform for mobile robots. Number of parts need to print:

- body (needs support) or bodysupport (already included with clearance 0.5mm but may create ugly interfaces)
- side x2, one mirrored (or side-taller, see below)
- sprocket, axle, idler, and all gears x2
- wheel x8
- link x62

optional:
- clip x4, for holding controller pcb with variable size on top of it
- hanger x4 for holding battery holder
- batholder for securing 2x 18650 battery holder
- boardholder (with more hanger x4) for placing something I have not think about yet

non printed parts needed:
- dc motor, 130 size, x2
- m3 screws 20 mm and 30 mm + nuts

After first try I found the tracks rather slack but if reduced by 1 link it would be too tight. So I modify the wheel suspensions to be 2 mm taller, but I have not tried it yet.

I use a 3 volt dc motor with 2x lithium at 8 volt consciously, and I use PWM to give the motors about 40% duty cycle to ke