A bellows assembly for a downhole tool includes a first seal ring, a second seal ring, and a bellows positioned at least partially between the first and second seal rings. The first seal ring, the second seal ring, and the bellows are integral with one another such that the bellows assembly is monolithic. The bellows is configured to expand and retract. The bellows is annular and has a diameter that varies over a length of the bellows. A material composition of the bellows varies over the length of the bellows.