Hey Airscapes, thanks for your reply.

I have tried flexible filament but it?s not grippy enough. A friend also suggested dipping the finger in silicone, but I was concerned about it degrading.

I?ve got another idea that I want to try out. Once I?ve completed my experiment I?ll share the results with you on here. If it works then it?s a cheap fix and users will be able to maintain it too