This is a very simple bottle cap magnet. It makes the bottle cap sit approximately 1mm above the surface so that it doesn't scratch. It was modeled for a coke bottle cap, but I assume it should work for any non screw off bottle cap 

It is made to fit 15mm x 3mm neodymium magnets.
I used these from amazon, but you should be able to use any 15mm x 3mm magnets:

https://www.amazon.com/dp/B0D2Q385PZ?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1https://www.amazon.com/dp/B0D2Q385PZ?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1