Here is a tutorial video I created describing how to build a SUPER simple robot. It is also programmable via the wiring. This was designed to be able to have the bare components and not need any special tools to put together. If you want to use some more robust adhesive to attach components, or use solder to connect the motors go ahead. If you don't have those things don't worry, they aren't used in the video. Let me know if you have any question at all! Enjoy.
Things You Will Need
2x 5-6v DC Motors
Some wheels for the motors (I 3D printed mine but you can cut them out of cardboard)
Some rubber bands
An axle (I used a wooden dowel)
A battery (I used a 2cell Lipo battery from an old R/C toy)
Some wires to connect your motors and battery
None, though some wire strippers would help unless you can claw at the ends.
You can use solder and get fancy if you have the means, but if not don't worry.