The rule is:
2b) Size limits: robots must fit completely (including aerial) inside a cube of the following dimensions
Fleaweight: three inches (76.2mm)
Antweight: four inches (101.6mm
Robots may only expand from their size limit once they are in the arena, and only if the expansion is instigated by remote control (i.e. not just by being springy).
I was suggesting that a robot that had an acetate sheet on the front that would not fit into the cube without bending and that relied on the robots weight to hold it bent until the robot reversed allowing to spring open was not within the rules.
First when we say a robot has to fit in the cube that infers the robot can just be placed in the cube without having to apply external forces to alter the robots size or shape.
Secondly the bit at the end of the robots may expand clarification (ie not just by being springy) excludes the method of expansion.