| name | prototyping-fabrication |
| description | CAD fundamentals, 3D printing (FDM/SLA/SLS), CNC machining, workshop skills, rapid prototyping methodology, and testing of physical prototypes. Covers fidelity levels, material selection for prototypes, dimensional tolerancing, assembly planning, and the iterate-test loop. Use when building prototypes, selecting fabrication methods, planning physical tests, or choosing between prototyping technologies. |
| type | skill |
| category | engineering |
| status | stable |
| origin | tibsfox |
| modified | false |
| first_seen | "2026-04-12T00:00:00.000Z" |
| first_path | examples/skills/engineering/prototyping-fabrication/SKILL.md |
| superseded_by | null |
Prototyping and Fabrication
Prototyping is the bridge between design intent and physical reality. A prototype is a testable embodiment of a design idea -- it answers questions that analysis alone cannot. This skill covers the full range of prototyping methods from cardboard mockups to CNC-machined metal parts, with emphasis on choosing the right fidelity level, the right fabrication method, and the right test plan for each stage of the design cycle.
Agent affinity: lovelace-e (materials and fabrication expertise), watt (mechanical systems and testing)
Concept IDs: engr-rapid-prototyping, engr-testing-methodology, engr-data-from-experiments, engr-failure-analysis
Prototyping Strategy
Fidelity Levels
| Level | Purpose | Typical materials | Time | Cost |
|---|
| Proof of concept | Does the idea work at all? | Cardboard, foam, tape, Arduino | Hours | $1-50 |
| Form study | Does it look and feel right? | 3D-printed plastic, clay | Hours to days | $10-200 |
| Functional prototype | Does it perform as designed? | 3D print, laser-cut, machined parts | Days to weeks | $100-5,000 |
| Pre-production | Can it be manufactured? | Production materials, production-intent processes | Weeks to months | $1,000-50,000+ |
The cardinal rule. Build the lowest-fidelity prototype that answers the question. A cardboard mockup that proves a mechanism works in 30 minutes is worth more than a machined prototype that proves the same thing in 3 weeks. Save high-fidelity prototyping for questions that require it: material strength, precision fit, thermal behavior.
What Question Does This Prototype Answer?
Before building anything, write down the question:
- "Will the gear train fit in the housing?" (form study)
- "Can the mechanism produce the required force?" (functional prototype)
- "Does the user understand the interface?" (proof of concept + user test)
- "Will the part survive 10,000 cycles?" (functional prototype with production materials)
A prototype without a question is a hobby project. An engineering prototype has a test plan before the first cut is made.
CAD Fundamentals
Computer-Aided Design is the standard tool for defining geometry before fabrication.
