I would never buy a kit that required soldering, because I'm terrible at it. But I like putting things together. I've assembled a couple of DIY keyboards, and I bought a Framework 12 laptop. It doesn't take too long (Framework estimated 15 minutes, but it was more like 45, because I am slow and methodical), and I like knowing what's inside it. The transition from “box of components” to “working system” always thrills me. And, though the repairability of a trackball is not a big issue, it's nice to know that what you put together can be taken apart, for example, to replace an SSD in a laptop.

I get it doesn’t appeal to you. Why do you think it shouldn’t appeal to anyone?

There are zero upfront no-questions-asked 3D printing services as well as such PCB/PCBA manufacturing services, but not a Buy Now style Mechanical Turk assembly line service, yet. So you'll have to do the non-scalable work and do the literal manu-facturing when it comes to tiny volume cottage industry products with no cash or volume to foot and amortize upfront costs. Which can be bypassed or minimized if it's supposed to be a kit and you only have to bag some parts. Also it blurs areas of responsibility in favor of the shop.

You’re on Hacker News, lots of us like to solder our own devices and spend time tweaking things. I’m right now waiting for my e-scooter tire to complete its 3d print. It would have been cheaper and way faster to just replace my tubeless tire instead of designing a whole airless tire system, prototype, print, mount everything. But it’s a hobby

Me