Either have it buildable from machine frame → wires → some kinda vendor board → Console screen & other components
or
Orderable from Req for X Dollars.
Say it can hold 10, 15, or 30 different things, and 1-30 of each thing, or, a separate limit for large, normal, and tiny things, like 5 large 10 normal 15 tiny.
or
Separate vendor board per vendor type: General, Engineering Typed Items, and Medical typed items- like how engie and medkits work.
This reminds me of one of TGMC great inventions: engi’s dispenser. A deployable backpack with great inventory space to compensate the need to deploy to use any of them, IIRC there was a medic equivalent with internal storage for chems that marines can chug directly or kits to heal when deployed.