I meant with the pleats, similar to what you see on an actual accordion, or in a bendy straw. It's how they did the joints on the Apollo space suits, for a vaguely similar application. The shape is sometimes called "bellows", but that's pretty confusing when it also refers to an air blowing technology that may or may not involve a diaphragm of any kind.

If you got enough range of movement with just a straight elastomer cylinder, that works, but if the pressure is pretty modest a variety of stretchy ducts made for HVAC or other home purposes are sold. I have some for draining rainwater, but they seem to break in stiff wind, so YMMV. You could also mold your own again.