Tank treads can be complicated, depending on what your recourses are, for instance a simple bot as shown above is easily made, but wouldn't stand up against last years competition. one of the teams at our regional last year used treads, their goal was to climb the steps, but weren't able to and ended up just pushing around balls. I personally favor treads for their easy drivability. And Ken, i could easily make the mounting brackets if you drew them for me, being i have a maxnc cnc milling machine in my basement, which everyone on my team seems to forget.

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Whats the difference between mechanical engineers and civil engineers?
Mechanical engineers build weapons, civil engineers build targets