Check these guys out if you are going to make a robot or some type of transporation device.
Even if you are not into robots, I think this platform could serve as a quick, already-made travel platform
for any type of machine you are trying to make.
They provide these robot platforms with wheels, motors, battery to get you started with different weight classes from 30 to even 220 lbs.
The platform can travel at maximum speed of 20mph with 24V DC power…
I am thinking of a Zedomax Battlebot