Not sure if I should admit it but I helped a mate build one. We got accepted at auditions based on work in progress but it never got completed, mainly as we liked engines and welding and nothing about electronics.
Was more scrapheap challenge than robot wars, ran on 2 2-stroke engines with diaphragm carb so worked inverted powering a dragster rear wheel made from a BMX hub shell on a T45 steel tube axle and using Land Rover bevel gears. Started with a power drill. The weapon was mass and speed. Tool steel battering ram and pivot steering. Noisy and dangerous, probably best it never ran…