If you like the metal kind for their weight, but not for the chafe, try getting the lead shot filled Ball Stretchers.
ITs a glove leather tube willed with shot that warps around the scrotum and snaps or velcros into a ring.
Because they have a RADIUS and are made of soft leather, you will find you can wear them all day without too much abrasion. ( still, take a day or two off now and then to let the skin heal ) Stormy Leather
makes the nicest ones, half a pound each and you can stack them
Or you can get a LOWER profile version that can be worn less noticeably from Backlash
Check attached picture
they come in 1, 2 and three cell widths and can be stacked. not as heavy as the Stormy leather style, but slimmer.
For those who really prefer the steel, but want to reduce chafing, try the wedding ring weights from Secret Leather
- they have a nice round radius that spreads the load out across more skin... I will usually wear one of these at the bottom of a stack of larger weights.