I tried elastics, but they either slipped off or cut off circulation.
Weights were interesting. I liked the constant tug, but attachment and concealment were problems.
I settled on tying/wrapping with very thick/wide white cotton shoelaces. I think they were 24 inches long. Easy to wash. I wrapped one lace around and around like on spool, tight enough for the stretch, but not cutting off circulation. Then I tied the ends together with a slip knot. I could wear it all day and night, and I loved the feeling.
But it turns out I did not love loose low hanging balls. Very uncomfortable sitting. So I stopped stretching after a few weeks, and they went mostly back to their regular hang.