If you plan to "manufacture" the SBR yourself, you will submit a Form 1 to accomplish that. GD's question refers to whether you are going to do it as an individual or if you are going to create a LLC or trust to do it. The reasons most people go the LLC/trust "route" are because their local chief law enforcement officer (CLEO) won't sign off the Form 1 and/or they want more flexibility in who can take the toys out to play. Currently, LLCs and trusts don't require fingerprint cards and photos while individuals do. ATF is considering some changes, but nothing has changed so far.
Once the approved Form 1 comes back, you have to engrave the manufacturer's name (you) and city/state on the receiver or barrel. The engraving can be done by someone other than yourself.
If you have someone else "manufacture" the SBR and then transfer it to you, the transfer would occur on a Form 4 instead of a Form 1. Whoever put the SBR together for you would engrave their information on the gun and your name/city/state would not appear.
That is a quick overview. You might want to read through some of the older threads for some of the discussions that have covered this topic.