First: Assuming you apply the premise that this system needs to be able to build most of its own parts:
How can that be actualized?
First principles are to reduce the problem to its simplest form.
So, less parts is better for the purpose of simplifying creating additional machines on the ones you have.
This is the “CubeFrame” it is the main machine chassis, but it consists of 14 part numbers and 3 sizes of fastener (not counting the backplane – a separate assembly) – this is highly intentional – since it allows this part of the machine to be made with a very short BOM and all the parts are sized to fit through a Cube for processing – the skin panels are all made from identical pieces of stock, cut 3 different ways (2 back panels, 4 side panels, 4 top/bottom panels, these can be easily altered to accommodate new functions or features.
As much as possible, this philosophy has been applied throughout all the basic parts of the system, with an open community, all these ideas can be improved.
This is one part derived from a standard piece of stock (493x98x3mm)
All the parts in the ElectricalTray made from that same piece of stock. (so far)
The side panels on the CubeFrame follow the same pattern, as do most of the other mechanical parts.
Having single purpose parts that are not used in multiple locations for multiple applications will be as as infrequent as possible, to keep BOMs short and maximize re-use, both of physical parts, and the procedures that make them.