Building a MacBook 12 inch
The MacBook 12 inch (USB-C) system will not reliably build from NetBoot because the EFI often requests packets larger than 10/100 Ethernet frames (9000 bytes versus 1433), and doesn't correctly negotiate down to a valid size.
This system is more reliably built from a IzzyStick (a bootable Mac build image).
Once everything is connected (see list below), boot the system to the IzzyStick (Hold the Option key at startup. Select the IzzyStick image and hit Return)
Plugs and Adaptors needed
USB-C VGA Multiport Adapter for the 12 inch MacBook
http://computershowcase.umich.edu/item.php?cat=138&item=610012&id=3678
Hub - 4-Port USB 3.0 with Attached Cable (or another other USB hub)
http://computershowcase.umich.edu/item.php?cat=65&item=522304&id=3149
Apple USB Ethernet Adapter
http://www.apple.com/shop/product/MC704LL/A/apple-usb-ethernet-adapter?fnode=8b&fs=f%3Dcable-ethernet-usb-usb20%26fh%3D4595%252B303f%252B45c4%252B30a3%252B30a6
USB Drive 32 GB
Used to create a macOS boot stick. More info can be found here on how to create this boot stick.
USB-C Power Adaptor
The system needs to be powered during build through the USB-C VGA Multiport Adapter.