I like the approach taken by the Soviets for the first version of the Krasnogorsk Horizont (1972 model): a plain hollow tube. The bottom could be unscrewed revealing a cavity in which an extra roll of film could be stored.
I trialled it on my Widelux. While that worked well and felt right, I did not want to risk breaking the plastic handle, lest my Horizont set then be incomplete.
As I was putting the Horizont handle away, Serendipity patted me on the shoulder: Mulling over alternate options, I noticed the plastic knobs that stop a door from banging against the wall. Incredibly, they have same shape and dimensions (incl. diameter), and are also hollow. Moreover, their rubbery plastic actually provides for a much better grip than the hard plastic unit used by Krasnogorsk.