I wanted something simple without any buttons and this is what I came up with. Just slip it on the cup from the bottom up and poke the handle through the slot.

Making a Foundation Half Double Crochet
https://www.youtube.com/watch?v=rR81vklEQ_0

Joining a Foundation Half Double Crochet in-the-round
https://www.youtube.com/watch?v=09_08oIMt60