If you enjoy this project, then I encourage you to buy my book, Rubber Band Engineer. It's full of more awesome and original projects crafted from household hardware. You can find it wherever books are sold.
Two robots face off and try to throw each other off of a table! It'll make more sense after you watch the video...
More footage from actual student-built JudoBots:
I call them JudoBots because of the way they seem to throw and grapple with each other during combat.
Although designed for children in grades 4-6, I think just about anyone can have fun with this. Even parents can't resist trying it out!
The bots are assembled from four components built separate from one another: the base, the stand, the arm, and the hydraulic system. The hydraulic system uses plastic syringes as pistons and water as the hydraulic fluid.