Roll assemblies for cotton harvesters and associated methods are disclosed. Example roll assemblies may include a unitary component that defines a plurality of slots. Bats and brushes may be removably retained within the slots. The unitary component may include a plurality of lobes with the plurality of slots defined therebetween. A central passage may be formed in a central portion of the unitary component. A shaft having an interlocking shape may be removably received within the central passage. In some implementations, one or more lobes are removably securable to the unitary component. End caps may be received onto the shaft and positioned adjacent to ends of the unitary component to assist in retaining the bats and brushes to the unitary component.