Help with finding the (perfect?) cage

You're unlikely to find the perfect size first time, and you'll also find that as you wear a device more, you do need to get a smaller size that you would never have been able to wear to start with.
Also, you can measure yourself as often as you like, but much of the comfort issues come from how much foreskin you have, how tight or loose your ball sack is, and how compressible your penis is. Most guys have no idea just how flexible and compressible a penis is before they try to confine it in a chastity cage.

A good strategy to start is to get a couple of cheap devices off the internet, if you buy devices of different sizes, then get them with the same fittings, ie both with padlock and post or both with integrated lock. Then you can mix and match the different size rings and cages, and so get a better understanding of what fits, is comfortable and wearable. Getting them from the same manufacturer will ensure that you can mix and match, as they usually use the same jig sizes to make all the models in their range.

So do your initial measurements, and get two cheap cages, one with a ring size one step away from the other, and one with the cage length on step away from the other. If you're lucky one combination of ring and cage will fit you like a glove and even if not, the difference between them will make you much understand much quicker what the differences are and what your likely better fit might be.

Most guys go through half a dozen devices until they find their perfect fit, so don't give up if it doesn't work out to start with.

 

I would try to look for some type of kit that has multiple rings and cages that are all modular in the material you want (I would suggest metal). As @bondinchas said it is unlikely you are gonna get a prefect fit on your first go around, but after experimenting with your kit & sizing over a couple months... I'd look at a custom device from a place like Mature Metal, Steelwerkz, or Bad Ass Work Room. These devices will be a lot more money, but it's worth it in the long run once you know exactly what you are looking for.

I prefer Mature Metal's Jailbird model the most.

 

The gap might be too large have you tried using a smaller ring if it came with multiple rings? I have had some devices where I would have the same issue if you can't drop a ring size you might have to look for a device with a smaller gap.

 

Your gap is definitely too large.
The difference in size between testicles doesn't really matter. All that goes between the rings is the scrotum and the vas deferens, what matters is that the gap is smaller than the smaller of the two boys, then when the smaller one can't escape, neither can the bigger one.

With a narrower gap between cage and ring which you do need, there's no predicting whether a larger, same size or smaller ring would be appropriate. It's annoying, but it's like trying to find trousers that fit. Some are too narrow in the leg, then you find a pair with baggy legs and the arse is too tight! In both cases, there's no short cut, you really have to try different designs until you find the one that fits.

 

If you use the next smaller ring, the geometry of the two rings will automatically reduce the gap.

Those of us that have tried numerous devices to get there usually find that we progress through smaller and smaller rings.

Hygiene is always going to be more of a chore with a plastic device. Plastic being not as strong as steel has to cover more skin for the same structural strength. Being porous, plastic holds moisture, warmth and humidity and creates a better environment for bacteria than steel. It's also much more difficult to clean once it gets stained.

 

Mature Metal has a ring sizing kit you might want to start there and find your perfect ring size, the look for a good stainless steel cage they are in my opinion better for long term wear.
Lots of good inexpensive cages on Amazon and ebay as well as Etsy.
Try them before buying a custom cage.
You will get a better feel of what you like.
And in my opinion stay away from hinged base rings they can pinch you pretty good

 

Ball trap cages will definitely do that, especially during an erection, I use a support strap belt style ans synch it up tight when I go to bed due to night time erections

 

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Ball trap devices are going to pull, as others have said ring size and gap may need reducing to help, I find a snug ring and minimal gap are best for me.

 

If you look at my pics, I'm wearing a non balltrap held on by a PA hook. This type of device can be held on by a glans retainer ring also. Check out pics by Iron78 to see a good Glas retainer ring cage. For most people, you need a glans ring or a PA even on a balltrap cage to keep from being able to pull out when soft.

 

They can be held on with a glans retainer ring. That is not a piercing. It is a smaller ring that fits tight behind the head of the penis and when the cage is slid over, it locks to the bottom of the cage. If the cage is pulled to try to take it off, the retainer ring pinches down behind the glans.

And like I said, even with a ball trap cage, without a piercing or glans ring, for many they are not really secure. Every cage I've had without a PA, I could just pull out of when soft.

 

Hi. I'm new to this kind of thing, so I'd like to try it out, too. Any recommendations on how to choose it?

 

Go to D H Gate or Alli Express, they have many types of devices. I would go with a stainless-steel device. Steel is easy to clean, and it is the most secure . I like the steel Nub or a flat cap device. Both can be worn for long periods of time. Steel is heavier than plastic so you may want to use a waist belt to relieve the extra weight and to make the device very secure.