[kirtar]

Any mechanism used to interact with the ball must be below the bumper zone or you will get a penalty every time you use it. However, if you for example, angled the top of your robot to affect how a ball would bounce off of the top of it, I don't think there's anything wrong with that.

Also, if you somehow manage to touch the tower without expanding beyond your normal configuration, you can hang any time you want without penalty, since being in contact with the tower allows you to expand to final configuration.