At first, I built a cage around an EV3 controller out of lego. Everything in that prototype was made of legos. On the cage, I put a lot of pipes. The long, bendy, grey ones, because that was the place, where the water was supposed to come out. Then, I built a frame and attached it to the cage. Then I put servo motors on the frame, and on the motors, I put wheels. I connected the wheels, so between the wheels and the frame was space, where a pipe could fit. After that, I made a clarifier model out of a cardboard box, by cutting holes in it and taping another cardboard box above it. Then, I took a curtain rod, put it on the model, then I put the rod inside the hole between the frame and the wheels. So, the rod would stay on the cardboard boxes, and the robot would dangle off the rod and move upside-down.