Separate the robot construction on body - body and attachments. Attachments should be small, light and most importantly for winning the competitions they should be pinless. In this category we group tutorials, courses and materials for different attachments that have proved to be useful.
Robot attachment that shows you how a circular motion could be transferred to linear by using a gear and a rack. The final motion is for pushing and pulling things.
The attachment could be built from LEGO Mindstorms EV3 and NXT parts.
Attachment used to transfer the motion from the motor from a vertical axle to a horizontal axle. Uses two gear wheels. Could be built with LEGO Mindstorms EV3 and LEGO Mindstorms NXT kits.
This robot attachment shows you how to limit the rotation of a lever. It uses two gear wheels to transfer the motion on 90 degrees.
It could be built with LEGO Mindstorms EV3 and NXT versions. Most of the time during competitions like FIRST LEGO League and World Robotics Olympiad you need a lever for just a limited motion