[EricH]

Touching the wall is legal, and having your robot expand under its own power is also legal (up to 60"). However, there is one minor detail. You have to fit in the sizing box in a self-supporting way. You might consider having a weak, springy latch on the part that springs out when you start driving, just to be on the safe side. Here is the rule on that:

<R06>

The starting configuration of a robot immediately prior to being enabled by the Arena Controller at the beginning of a match is the basis upon which a robot will be inspected for compliance with the maximum allowed size. This configuration of the robot must fit within a FIRST Sizing Device that has the following inside surface dimensions: a flat, level rectangular base 28 inches x 38 inches, and a height of 60 inches. Other than resting on the floor of the Sizing Device, no part of the robot may break the plane of the sides or top of the Sizing Device during size inspection. The robot must be self-supporting while in the Sizing Device.

Oh, and you must keep any springs on the robot for the entire match (<R08>).