Getting a grip on the plectrum

How do you prevent a plectrum from slipping in your fingers as you play? For some this is not a problem and for those who do experience this there are several solutions. Some players go for ‘Dunlop’ type plectra which have a moulded grip at the top. Unfortunately these tend to be made of soft plastic or nylon which, in my experience, creates a scratchy sound and poor tone. A couple of other solutions are
1. Sand the top part of a smooth plectrum to create a rough grip leaving the point smooth.
2. Wrap a piece of medical sticking plaster round the top of the plectrum to absorb moisture and provide a secure grip.
3. Drill a hole through the centre of the top of the plectrum. This really helped a student of mine recently and the problem was solved.
4. There are some plectrums I discovered in Germany and available, I think through through the Trekel web site which are thick soft plastic with a grip and although I personally don’t use them I know some players who really like them. They come in blue and white according to hardness.

Any suggestions from readers will be gratefully received and passed on here.