Wire wool
[edited to say: just read the post that lists what is banned - never mind, maybe in another less restrictive future series!]
Intrigued to know what is allowed in terms of weapons, but one thought I've had in the back of my mind for "when I go on Robot Wars" is to puncture a hole in the opposing robot using a large hollow needle, and fill it with wire wool, forced down the needle in a similar manner to that used to install cavity wall insulation. Before the needle is retracted, the wool would be ignited to give a lovely smouldering mess on the inside, hopefully cooking a few critical systems in the process.
I suspect that incendiary devices might not be allowed though, as I don't recall anyone other than the house robots ever using a flamethrower.
Biting the hand that feeds IT
