I'm looking for the simplest way to build a gantry that travels back and forth on the X axis only without it being hooked up to a computer. It will be belt driven and controlled by an 18v dc drill motor.

I was thinking about using an "on-off-on" switch at each end of the gantry slide to reverse the direction of the gantry, but I think the motor won't last long if I do that. I need something to slow the motor at each end before it reverses direction.

I've thought about Hall sensor's, 555 timers, limit switches etc., but they seem complicated being that I don't know much about them. Just want something simple.

Any idea's?