I am working on what is probably the easiest robot in the world, and i almost have it done. this took longer than expected because i added a switch to it.i cant get an image just yet, because it fell off of my bookshelf. srry
I made seven so far, and I have a video somewhere on my computer of all 7 in an enclosed wooden "arena" and me turning them all on at once, it looks pretty cool.
One two of them I added an OpAmp and 1 bumper switch so that when it touches something it completely stops
oops I forgot to mrntion that most of mine are made using sweeping brushes and ‘normal’ motors with a wheel with a weight added to one side. they are usually cheaper than toothbrushes with pager motors, are easier to modify and less fiddly to work with.