various steel male chastity cages exist
i have not tried the vice but the 6000's do indeed pinch
the issue is the hard edge on the ring rather than a completely rounded one
various steel cages are ok however the rings are all 40 45 or 50mm
Stainless Steel Birdcage Male Chastity Cage Lock & 3 Rings Black US SHIP
is an ebay search for a typical one
the 45 is too big for me and 40 is a bit tight
but 40 will work
there is a new cherry picker that has more sizes which is more expensive and is plastic 3d printed
that may be best but have not tried
recommend this but get one with 3 rings not 1 and try all
be willing to wake up at night and use ice to reduce size of scrotum
other person here sized for comfort when awake not to be tight enough to stay on