I’ve just created and checked into git the templates we’ll use to communicate with the factory about key layouts.
You can find them here:
Red shows the keycaps themselves, including the top profile, the outline, the homing dots and the keystems.
Yellow shows some orientation features.
Guidelines on where to place the key labels are in black.
I’d welcome cleanup to the SVG template 
Feel free to ask me questions about it here, though with the baby, my attention is a little scattered.