From: Newcastle, Australia
In the past when I've wanted something that can't be readily bought anywhere, I've made my own.... For example, I always wanted a quality, old style block & tackle (lifting device) for suspension scenes. But not even the internet was much help - which is probably the path that's brought you here.
I've now got what I wanted but custom builds are not an easy path for most. To give you an idea of what I mean, I work in a small engineering/machine shop and so was able to do everything myself. I bought 2 stainless steel swivel-hooks on ebay and 6 sheaves (or rope pulleys) and a self-locking cam-cleat from a sail-boat store. Throw in assorted stainless steel bolts & nyloc nuts etc and around a hundred hours of sheet-metal work and machining - and presto, job done. Ok, I'm a quality nazi, so it is rather over-built but it does look the business - intimidating, even. Not a bad thing in this lifestyle, ay.... ;)
For any co-workers nosing around, I was just making an old-school lifting device. Which is where your custom toy would be more problematic if you can't do it all yourself, or know someone who both can and understands - or is at least discrete. And unlike my project, you hafta factor in that such a thing likely isn't gonna be a "one size fits all" kinda build.
That said, if you've got money to burn and can at least draw a basic design (with dimensions added), there's bound to be kink businesses that can accommodate, no questions asked. That, you can find on the internet.
Never underestimate the persuasive power of stupid people in large groups. <unknown>
Your food is for eating, not torturing. <my mum> (Errm, when I was a kid)