Abstract: A container 401 comprising: a base 402; and a sidewall 404 extending from the base 402; wherein the base 402 and the sidewall 404 define a cavity for containing a consumable; the sidewall 404 comprising at least in part a sidewall element 406 deformable between a compressed state in which the cavity has a first volume and an uncompressed state in which the cavity has a second volume; the sidewall element 406 configured to be bistable such that the sidewall element 406 will remain at rest in equilibrium in both the compressed state and the uncompressed state; wherein the sidewall element 406 is movable between the compressed and uncompressed states by input of an activation energy to the container 401.