Hydraulic robotic armthis hydraulic robotic arm is a great gift for both kids and adults its a brilliant and simple example of how hydraulics work in real lifethe model robotic arm is similar to what you may or may not have seen in the marvel comics and film iron man and who wouldnt want to build their ownmade from die cut ply wood the pieces are precisely cut and assembly should take somewhere around one or two hoursonce assembled and youve added water to the system the hydraulic arm