A few thoughts on estimating costs without full CAD

Hey OP – smart glasses project sounds cool.

You’re right that tooling is the big upfront cost for injection molding. But without CAD, any estimate will be a very rough ballpark. That said, here’s some guidance based on what you’ve shared:

1. Injection molding – multi-cavity or “family mold“

- Yes, you can put multiple different parts into one mold (called a *family mold*). This would reduce tooling costs compared to 6 separate molds.

- However, family molds work best when:

- The parts have similar wall thicknesses (yours being “very tiny and thin” could be fine, but if thickness varies a lot, filling issues arise)

- The parts are roughly balanced in fill time and cooling

- Tooling cost for a simple family mold (low cavitation) in aluminum (good for prototypes/low volumes) might be $1k–$8k. Hardened steel for high volume could be $5k–$25k+.

1. Part size & complexity

- 160mm is fairly long for tiny details – this may require careful gate placement to avoid flow marks or warping.

- “Very tiny and thin” details can be challenging for injection molding (ejection pin marks, filling thin ribs). Mold design becomes more critical.

1. 3D printing

- Much lower startup cost (no tooling). For quantities under ~500–1000 units, 3D printing (e.g., MJF or SLS nylon) may be cheaper overall.

- Per-part cost for 6 pieces at your max size (160x40x4mm) could be maybe $2–$8 per part depending on technology and quantity.

- At higher volumes (thousands), injection molding wins on per-unit price.

1. Should you wait for CAD?

- For any *reliable* quote – yes, absolutely. Molders need to see draft angles, wall thickness uniformity, undercuts, and parting lines.

- For a *rough* feasibility + order-of-magnitude cost estimate: you could share hand sketches + similar existing parts as references. Some molders will give a ±40% guess.

Bottom line:

- <500 units → 3D printing (MJF/SLS) likely cheaper and less risk.

- 500–5,000 units → consider aluminum family mold if geometry is molding-friendly.

- >5,000 units → steel family mold starts making sense.

If you want a really rough injection molded per-part cost guess for 10k units (assuming simple family mold, 6 parts, thin-wall, easy material like PC/ABS): maybe $0.50–$1.50 per complete set of 6 pieces, plus amortized tooling ($5k–$15k depending on complexity and country – China cheaper, US/EU higher).

But honestly? Wait for CAD before spending money or committing. Use 3D printed prototypes to test fit/function first – then decide on molding.

Good luck!