By Paul Vizzio
This project is a good example of how cost reduction actually happens in hardware. Not through negotiation or switching suppliers, but through design, iteration, and working closely with manufacturers from the beginning.
The RemieLock mechanism on the RemieDog leash went through 28 iterations, ultimately reducing the cost from about $45 per part down to $2.50. The process wasn’t linear, and it didn’t happen all at once. It was a sequence of design, review, and refinement cycles across different manufacturing approaches.
This post walks through that progression.
Initial Design and Prototyping
The first step was simply to make something that worked. At this stage, cost wasn’t a factor. The goal was to develop a mechanism that functioned correctly and felt right in use.
We started with 3D CAD and multiple rounds of 3d printed prototypes, iterating quickly to validate geometry, motion, and ergonomics. The focus here was entirely on function — making sure the locking mechanism behaved the way we wanted and integrated properly with the leash system.
These printed iterations were critical. They allowed us to test button geometry, travel, and how the webbing interacted with the locking surface — things that are much easier to evaluate physically than in CAD. Over several versions we adjusted clearances, refined the locking profile, and improved how the mechanism engaged under load.
Once we had a design that worked and appeared manufacturable, we created full engineering drawings and sent them out to manufacturers for review and quoting. This step was built into the process from the beginning — getting supplier feedback early rather than waiting until later.
The initial quoted cost came back at roughly $45 per part at a 1,000 unit minimum order quantity.
Design for Manufacturing (CNC)
From there, we worked directly with manufacturers to refine the design for CNC production. This is where Design for Manufacturing (DFM) starts to have a real impact.
The original concept was already set up to avoid tooling — two parts, minimal operations, and as compact as possible — but there were still opportunities to simplify geometry, reduce machining time, and eliminate unnecessary features.
We iterated on the CAD, updated drawings, and sent revisions back for feedback and re-quoting.
After several rounds, the cost came down to around $20 per part at 1,000 units.
At that point, the design was already optimized within the constraints of CNC machining. Further improvements were incremental, and it became clear that continuing down this path wouldn’t get us to the target cost.
Changing Manufacturing Approach
Instead of continuing to refine the CNC design, we stepped back and reconsidered the manufacturing approach entirely.
We explored existing cam lock mechanisms and worked with suppliers who specialize in them, but none of the off-the-shelf solutions fit the application. Issues ranged from button direction and geometry to material interaction and integration with the rest of the system.
That led us to move toward a die cast design.
Initial Die Cast Design
The process at this stage looked very similar to the original development phase.
We created a new design around die casting constraints, focusing first on function — making sure the mechanism still worked — before worrying about cost optimization.
Once we had a working design, we generated drawings and sent them out for review and quoting.
The initial quote came back at approximately:
- $5 per part
- 1,000 unit MOQ
- $750 tooling cost
This confirmed that die casting was the right direction, but the design still needed further refinement.
Design for Manufacturing (Die Casting)
From there, we repeated the same DFM process — but this time specific to die casting.
Working with suppliers, we iterated on:
- Geometry simplification
- Draft angles and wall thickness
- Part consolidation
- Assembly considerations
Each round involved updating CAD, revising drawings, and sending the design back out for feedback and updated pricing.
This stage is where most of the cost reduction actually happened.
Final Design
After multiple iterations and supplier collaboration, the final cost came down to:
$2.50 per part at 500 units
At this point, the design, process, and assembly were all aligned with the manufacturing method.
Patents
One important aspect of this project was starting the patent process early. The core concepts and variations were covered throughout development, rather than waiting until the final design.
That allowed us to iterate and work with suppliers without exposing an unprotected design. And also to freely post about it here.
Takeaway
Cost reduction followed the same pattern twice in this project:
- Develop a working design
- Get manufacturer feedback and initial pricing
- Iterate through DFM
First with CNC, then again with die casting.
The key difference between the $45 part and the $2.50 part wasn’t negotiation — it was going through that process fully, and being willing to change manufacturing approaches when needed.
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