How much of a RepRap printer can a growing seed shop make itself?

research/selfrep-closure

Part, mass and cost closure of the RepRap Prusa Mendel (iteration 2) for three seed shops: printer alone makes 18 of 51 part lines (35%), plus router and laser 43%, assumed-mass closure 22%; casting helps only with brass bushings. Mass and cost inputs assumed. Stylised.

8 tests

What it found

The RepRap Prusa Mendel (iteration 2) bill of materials (51 part lines, from the RepRap wiki) against three seed shops. A printer alone makes 18 of 51 lines (35%); adding a CNC router and laser cutter reaches 43% of lines and, under assumed masses and costs, about 22% of mass and 16% of cost; casting helps only if brass bushings replace LM8UU bearings (45% of lines, 24% of mass). Motors, electronics, rods, bearings and fasteners stay vitamins. Stylised: the wiki gives no masses or prices, so those inputs are assumed and shown with a sensitivity range, process assignments are judgement, and only the printer is decomposed.

A figure from its own output

Figure produced by research/selfrep-closure: closure_by_shop — selfrep-closure/experiments/closure_by_shop.svg, written by the project's own experiment code.

Paper, code and results

More in Self-replicating manufacturing

Which machine should a seed shop add next, and does a greedy rule find it?Which machine a printer-only seed shop should add next under a budget: greedy closure-per-price vs exhaustive search; same choice on the real 3-machine instance, optimal in 72–94% of 500 synthetic instances. Machine prices assumed. Stylised.
How fast does a replicating printer shop grow when its vitamins must be bought?Discrete-event and fluid growth of a replicating printer shop with imported vitamins: doubling time falls roughly as 1/budget until machine time binds (about 53 h in the simulation), failed builds cost about 1/(1-f), and closure helps most when imports bind. All inputs assumed; Lackner and Wendt comparison not done. Stylised.
When should a replicating shop stop copying itself and start making goods?Optimal split of a replicating printer shop's time between copies and goods: copy flat out, then switch one e-folding time (about 50 h) before the horizon; constant splits get 9–27% of that value, smooth ramps no better. Cash-limited cases switch about 50 h from the end. All inputs assumed. Stylised.
How much imported material can recycling save a self-replicating printer shop?Mass and energy balance of plastic and aluminium recycling for one RepRap copy (stylised, assumed process parameters): vitamins stay about 75% of imported mass, recycling the shop's own scrap cuts imports a median 3%, and only retired-machine plastic changes the plastic import much.
How many printer copies does it take for a shop's recycling machines to repay their own imports?Payback of recycling machines with their own assumed part lists (stylised): about 100 printer copies on the shop's own scrap, 12–31 if retired machines' plastic is recycled.
Does pricing a shop’s imports, instead of weighing them, change when its recycling machines repay themselves?Recycler payback priced instead of weighed (stylised, assumed prices): plastic pair 98–111 printer copies on own scrap, furnace 203, 10–26 with retired plastic.

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Other research topics

Proper scoring & elicitation28 Effort & peer prediction9 Verification games & slashing19 Detection & tolerances14 Markets as routers13 Prediction-market design9 Paying contributors8 Decentralised training systems23 Digital twins & sim-to-real164 LLM chip design loops40 Robot manufacturing loops53 Ambient AI assistant46 Self-replicating manufacturing34 Simulation-first design64 Engineered clothing45 Task-specific AI accelerators40 Algorithmic chip-design loops42 Open-source purpose-built robots44 The software-engineering loop43 Adversarial human imitation41 Open-source residential construction41 Autonomous multi-angle capture34 Sensing, imaging and 3D31 Energy supply and dense energy storage39 Robot societies among people31 Agentic co-design of low-cost robots27 Laundry-hanging robots25 Machine learning on qualitative data23 Robots on the building site27 Civilizations & group psychology1 History & human sciences1

Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.