What's the best material for making handles for crochet needles?

I don’t use any myself but drummers have all sorts of tapes, wraps, foams, potions & putty for their sticks.

Condoms help avoid those problems.

Love “Hide&Drink”
I like the little muslin bags stuff comes in. The products are guaranteed for life.
Did you see the little dachshund dog key fob? Makes a good gift. And a fun thing to own. :dog:

I’ve played with that before. It takes awhile to get it right. Kinda janky.

Harbor freight has it in-store fairly cheap if you wanna test it.
I did dozens of cheap chopsticks to learn how.

Great company!! Each item is handmade and comes with a card with the person who made it name .

I’ve purchased several leather vape pen cases for me and as gifts. Their canvas tote is my every day carry.

Foam clay might work for you. It’s like polymer clay but softer and less dense. Cosclay is one brand, but search “foam clay” on Amazon and you can find many brands. If your hooks are the kind with a size-stamped wider middle bit, the clay should stay in place as-is (after baking). However, if the hook is just smooth metal (no 3d shape to cling to) you might need to coat it with a thin epoxy clay layer or heat-resistant superglue first.