There are threads and videos on how to build them and what parts to immediately throw out and replace with OEM, depending on the brand and model. You can get a pre-assembled one which shows you how it goes together, but then you should tear it down, inspect every part, get OEM replacements for any weak parts, and rebuild it.
I looked at building some for the experience, but parts, labor, and OEM parts makes the cost more than an actual STIHL, and it will only make 80% of the power (or less, depending on the carb) and perhaps be good for 500 hours, at which point it should be torn down and inspected with any suspect parts replaced. I've heard STIHL saws should last 3,000 to 3,500 hours of hard use, add another 1,000 if they're well cared for, less if not let warm up and cool down. Clones... well, replacement saws are inexpensive.
The clone saws generally aren't nearly as fuel efficient and need a heavy oil mix, so those costs alone are significant detractors, plus the maintenance costs for a small operation...I think you need a large operation for that to make financial sense. With people porting STIHL and Husqvarna for more power so they can generate more hourly income I'm not convinced clones are cost effective.
Personally I'd rather buy a used OEM on the cheap and rebuild it, or a new OEM and have something really light and powerful as my body appreciates such things.
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Seperate from all that, the forced labor and dictatorialrule components of the regime are immoral. I don't want to support that, only to risk being consumed by it.
