This book was written to help people designing and building small combat robots in the UK insect classes. These cover mainly Antweight robots but also include Fleaweight and Nanoweight classes. It outlines the various types of combat robots describing both construction methods including 3D printing and parts with details of the electronic and mechanical parts required. It is written in a way that people new to the hobby should be able to understand it but also includes data useful to existing builders. All the example robots have been scratch built by myself over a period of around 18 years.