# Five Levels of Building Hardware Turning a design into a working object takes five separate skills. Each level is solvable, but each must be solved on its own. — Christian Keil's "write access" framework | Level | Name | What gets hard | |---|---|---| | 101 | COTS parts | Find compatible off-the-shelf parts. Design the connections. Buy them. | | 201 | Custom parts | Translate CAD into machine instructions (CAM). | | 301 | Electromechanical assembly | Tolerances stack. Teams and schedules must sync. | | 401 | External vendors | Custom parts from suppliers you do not control | | 501 | Massive scale | 1 unit and 1,000,000 units are different problems. | ## 101 · COTS parts - Availability is a design constraint. - Falcon 1, 2006: a hot fire waited on one capacitor. The only stock sat ~6,000 miles from the Pacific launch site. ## 201 · Custom parts - A machinist turns the engineer's CAD into CAM: stock, workholding, tools, cutting strategy. - This is artisanal. Variability here causes translation errors. ## 301 · Electromechanical assembly - Every part can meet its drawing and the assembly can still fail. Errors compound and correlate. - Parts must arrive "not before and not after" they are needed. ## 401 · External vendors - Almost no one should build their own fab or copper mine. - SpaceX, the vertical-integration champion, has 591 supply-chain staff and is hiring 128 more (LinkedIn, Sep 2026). ## 501 · Massive scale - Part and process variability matter more. - Financing for machines and inventory comes far in advance. - Assembly, integration and test need trained people or programmed machines. - Vendors hit capacity limits. > [!note] Why it matters > A model can master pure design inside a computer. DFM and levels 201–501 need contact with the real world, so models master them later. ---- tags: #boat #deeptech links: [[Superhuman Hardware Design Is the Easy Part]] [[Industrial AI MOC]] [[Precision Manufacturing]] [[Defense Supply Chain Fragmentation]]