There's SEEED Studio, in Shenzhen. They make PCB boards and assemble them. If you design using only parts in their Open Parts Library [1], they offer quite fast turnaround. They have ARM and ATMega CPU parts. They can also source from DigiKey and Mouser. They have a Design for Manufacturing manual, with lots of information on tolerances.[2] They'll hand-build one-off prototypes for you. Upload your Gerbers and BOM, and they'll give you a quick quote.

Of course, all this assumes you can design a working board. It's not inherently difficult, but there's a considerable learning curve. There are lots of online resources. For board design, there are lots of packages. I use KiCAD, which is open source, but Eagle is probably more suitable for pro work. (KiCAD is a good package, but the component footprint libraries are not that complete and may be somewhat off.)

(I've used them for blank boards. They do a nice job, but it's not super-fast. All their boards have been good, although once, by mistake, I got boards intended for someone in Japan, and they got my boards. Seeed re-made the boards and shipped again.)

[1] https://www.seeedstudio.com/opl.html [2] https://statics3.seeedstudio.com/fusion/ebook/PCB+DFM+V1.0+....

For one-off boards bigger than a few square inches I like 4PCB.com. $33+shipping for a 2-layer board, 5 day turnaround, up to 60 square inches for the fixed price. Minimum quantity 1. For contrast Seeed charges $4.90/sq inch for 2-layer and 5-day turn, minimum quantity 5. $66 for their 4-layer boards, though "only" 30 square inches. And they have a 1-day turnaround bare-bones prototyping service: those boards have no solder mask, but they credit the price of the bare-bones boards to your production order, so it ends up being a fast PCB prototyping service that only costs shipping). They're in the US too, so shipping is faster than the Chinese companies.

There are tons of board houses. What's unusual about Seeed is that they will do one-off assembly for a reasonable price, provided you design to their standards.

True, just mentioned 4PCB because they've had very good service in my experience (as a hobbyist/student). I've also used Seeed, they are quite nice, especially for small boards.

This reminded me of pcbshopper.com, it's a pretty neat comparison service for PCB houses. The data isn't always perfectly accurate though, especially because it doesn't take sales or other special pricing into account.

> If you don't understand your stack fully, things can get bulky and expensive fast.

Ironically, software really does fundamentally suffer from the same problem too. It just so happens that today's hardware is so powerful relative to most use cases these days that most developers don't run into those problems, until they try to scale (or they scale successfully, but as a result of the success now have the money and incentive to start caring about formerly tiny problems)