Let me elaborate a little. You can build more than one for personal use such as one each of a pistol, carbine, rifle, varmint, etc. (for example). But technically, you can not transfer the "gun" (lower) you made to anyone else unless it is serialized and through an FFL.
You can not also make (machine) an 80%-er for anyone as you are now a "manufacturer"... This would also apply to someone having an "80% build party" where everyone puts their lower into a jig and a CNC cuts it out after they press the button.
You're info is mostly correct I think, but maybe not exactly.
You can make all you want for personal use, but if you got tired of it or ever transferred it, you can't sell it unless you pay the FET (tax) which was 11% I think. And that's all that it boils down to I think. As always, the gov't has their hand out and wants their "fair share".
http://www.ttb.gov/firearms/background.shtml
It would not have to be transferred through an FFL to my knowledge because it's a personally owned gun, just like any other gun you already have unless a state requires all transfers. Even if not, you would need to take reasonable precautions that you're not selling it to a felon or prohibited person for obvious reasons all the same.
You would have to engrave the required 1968 GCA info onto the receiver for FET purposes because that's how they check if the gun is in compliance is the serial just like the NFA branch does (name, make model, serial, etc) but there is no FFL requirement that I know of.
Keep in mind, there is probably a thin line of how many you can make and "get tired" of and the timeframe you can do it in. I don't know those answers, but since none of that pertains to my intent on making my own receiver (for me to keep), is moot.