Considering a Custom Design

That's quite the large opening at the end there. May I ask why that's there?

 

It has a diameter of 2cm. That's big no matter who you talk to. That's 4/5 of an inch.

 

I'm just saying, you could cut that measurement in half and it would still be very large. 1cm would be plenty enough space for peeing. My current cage has an opening that's only 1/2cm and while I do have to adjust to line things up occasionally, peeing is no problem and rarely a messy spray. So 1cm should be no problem. 2cm just seems excessive.
Also, is there six bars or eight? The two perspectives don't agree.

 

The ring at the tip wants to be much smaller, you'll potentially have all sorts of problems if it's that big. I'd suggest 10mm which should work much better, any larger and you'll be pushing through a lot, painful when you try to get hard, and you'll also get lots of friction on clothes.

6 bars around the sides also might give a little too big a gap between the bars.
For a 35mm diameter at the entrance to the tube, that will give a circumference of 110mm, which would be 110/6 = 18.3mm between the bars at the ring. That's not accounting for the thickness of the steel bars, so a gap of say 15mm.
If you had 8 bars, then it would be just under 11mm, which is still a large enough gap to get skin folds poking through. Alternatively, you might want another ring or two parallel to the bottom and tip rings to keep you inside. If you're circumcised then not so much of a problem, but if you're uncut, then you need to beware of loose skin being able to poke out.

It's also not clear whether the bars form a cross at the tip, or a hollow circle. I presume a hollow circle, your two views look like they're two different devices!
If you're going to ask someone to build a custom device, you ought to have much more accurate drawings, for the size you should really do an exact 1:1 scale drawing rather than a freehand sketch. As you say, it would be an expensive mistake if the drawing was interpreted incorrectly.

 

I noticed the gap is 13mm...that’s half an inch. That is a huge gap.

I love the idea of designing your own cage, but do you wear a cage now? Is it similar in fit? I guess what I’m getting at is your non custom cage that you wear now should be somewhat close so that you know what to tweek.

I don’t know your penis dimensions so I don’t know if the rest of your design works, but I would be sure before spending that kind of cash on a custom device.

 

I sounds to me like you really ought to buy a ready made cage smaller than the one you have first. Until you have a much better idea of exactly the size you need to be comfortable for you long term, you will be wasting money trying to design a custom cage.

A difference of just a few millimetres can make a big difference to the comfort of the base and tube rings, I really don't think you're anywhere near knowing accurate enough measurements for a custom device.

 

My gut reaction is that with a 20mm (3/4") opening at the end, when you become erect your penis is going to poke through and become very uncomfortable.