Best option for long term

Have a look here: https://happy-marriage.neocities.org/device-table.htm and you'll see a few that are made of plastic but still have a relatively open design. Some of them were already mentioned here. (For me personally, it has never worked though and there was always some degree of smell in the plastic devices...)

 

Given the age of this thread, you might want to go back and revisit some of the other posters, 3D printing has come on a huge way since 2018, my 3D printed device is amazing!

 

I’m wearing a cobra knock off from Amazon. The lock is a little loose but is comfortable, easy to clean. Can’t beat the price.
FYJENNICC Upgraded New Material Cobra 2.0 Male Chastity Device with 4 Rings Black (Nub) https://a.co/d/6F7NNVS

 

The problem I find with metal devices, by the end of day everything is hanging low and I don’t want to wear a belt to keep the cage close to the body.

 

I know that problem well but plastic hasn't really solved it. The plastic devices stay up for a bit longer but once the scrotum decides to relax it will all drop down due to gravity, now matter how light it is. (And a tighter base ring is not possible at some point because it still needs to be wearable without pain when the scrotum decides to be tight or during a night time boner.)

 

I’m only 6 months into using a cage on a daily basis. I’ve tried a few different ones, but I found the original cage I purchased is the most comfortable. It’s a kink3D cobra cage. They are open and no metal except the small tumbler lock.