My goal was to make a robotic structure based on a tank frame. This tank should be sufficiently large and especially light enough to climb stairs, whatever they are, and even those with nosing. These imposing a great height, see my previous videos. With a length of 85cm and a weight of 2.5kg, I feel I have reached my goal. Furthermore an additional charge of 1kg is possible and will allow additional batteries or any component for a particular application. This 1kg load is a maximum as you can see in my video, it struggles to climb stairs. For the tracks, I used D joint (window joint) as shown in my previous videos. Thank you for your feedback. Settings and detail components with their weight: Length 85cm Width 48cm Height 22cm Chassis Weight 1300g EV3 + 165g battery 122g 4 large servos 82g x 4 = 328g Infrared receiver 20g Cables 44g Track with D joint 272g x 2 = 544g Front tank angle 35°