With this mod, you will be able to reduce the parts necessary to build a SMARS robot.
You will save 2 wheels and 16 track segments. It also gives you more agility and movements precision (especially with some rubber rings on the front wheels).
To build this module, you will need an extra component:
-1x 8mm steel ball https://goo.gl/SHkYf9
If you like my projects, just tip me or support me buying the material from my links, it will not cost you extra money and you will allow me to finance new projects! I would really appreciate it!