Thumbstick Cap Replacement for FJ06k-S(Valve Index Controller)?

Hi! First time here so sorry if I lack any proper etiquettes with the question..

With model reference: FJ06k-S in mind...

Problem: The thumbstick cap for my Valve Index Controller fell off and my cat chased and bit it to death so its unusable.

Question: Any recommendations on which caps I can use to fit over top and replace it?

Clarification: It doesn't have to be a whole switch, quite literally the plastic that fits over top of the stick that comes out of the switch. The flat thumb rest with a hollowed out tube underneath it that I can fit over the switch.

Attempted Solutions:

1. I've tried the xbox pro controllers cap, but they have 4 indents inside that make it unusable and no matter how hard I try to sand it, it wont. It's too tight.

2. Electrical tape bundle, but it looks ugly and stupid and the sensor doesn't work through it.

3. Make a fake cap out of plastic and just try to deal with it, but seems to be such a half butt solution.

4. Repair the actual cap itself, but it's in pieces and not worth the effort.

5. Search online for many caps but they're all too tight, or I haven't found the specific right size for.

6. Try to remove one from any other controllers, but they're all one piece, so it's not a viable option.