Well Creeper... just finished my AR build about a month ago... and though I didnt do anything really out of the ordinary I did try to build a Spikes Tactical OEM gun. By that I mean using as many ST components as physically possible. Though by no means a "complete" ST gun I was able to use about 90-95% ST components.
It was a lot of fun and required quite a bit of sourcing the parts. I believe I ended up doing business with about 5 or 6 different companies. Alot of times I could find a ST part somewhere else besides ST. In fact ST removed a few of the items from their site that I was able to find elsewhere.
I will be starting my another build soon and I am thinking maybe doing a Daniel Defense gun since it seems they are another MFG I can get about 90-95% complete with DD parts.
Perhaps one of these days I will find some MFG I can build with 100% oem parts but I am a bit pessimistic lol....