Need advice on cb 3000 - balls are sliding through the ring

Hi guys. I noticed that sometimes ( if cold for example) balls can noticably reduce size and scrotum also becomes small and hard. So balls just slide through the ring.

Im trying to wear the device for long time so putting smallest ring is challenging - it rubs scrotum. Also i cant buy metal device because of this
- its not cheap and there is a risk of rubbing or sliding off.

Heard something about packing balls in a condom but dont know how it is done.
Will appreciate any practical advices.