A part can be 3D-printed, machined, or injection-moulded — and none of them is always cheapest. Each has a fixed cost (tooling, setup) spread across the run, plus a per-part cost. Scrub the production volume and watch the cheapest process change: the printer wins for a handful, the mould wins for a million.
cost/part = fixed/N + per-part. Node-verified: 3D print (no tooling) wins at low volume, CNC in the middle, injection moulding (cheap parts, $15k mould) at high volume; crossovers near 100 and ~5,800 parts. Log–log axes. Built on the reusable probe.js primitive. · Institute for Physical AI @ BMI