By Paul Vizzio
In this blog we’ve covered a lot of individual parts of product development — CAD, prototyping, sourcing, and cost reduction — but fewer examples of how those all come together in a real product.
In this post we’ll walk through the development of the RemieDog Sutton Slide Leash, from early concept through prototyping, sourcing, cost optimization, patenting, and production.
Although the final retail product is sold under the RemieDog brand, the product development work described here was done through Vizeng. Since I run both companies, this project is a good example of using an in-house consumer product to show the full engineering process from idea to market.
This follows a similar structure to our earlier full-project breakdowns like the 3D Printed Mechanical Watch design study, but with a stronger emphasis on taking a mechanism all the way to a manufacturable consumer product.
Initial Concept Development
This project didn’t start as a generic pet product idea. It started as a day-to-day use problem.
We live in Manhattan, have a dog and a young kid, and found that standard leashes were frustrating to use in that environment. We were constantly switching between normal walks, pushing a stroller, passing the leash back and forth between my wife and I, and navigating crowded sidewalks and traffic.
Most leashes assume a single use case: one person, one handle, fixed length. That did not match how we were actually using one.
At the same time, we had no interest in making something that already existed. If we were going to develop a new product, it had to be meaningfully different and solve a real problem better than what was already on the market.
That led to the core idea behind the Sutton Slide Leash: one leash that could transition between wrist, waist, and cross-body configurations without needing multiple products.
That requirement drove the development of the integrated adjustment mechanism that became the RemieLock.
CAD (Computer Aided Design)
With the product direction established, we moved into 3D CAD.
Early CAD models explored:
- Strap routing through the mechanism
- Locking geometry and engagement surfaces
- Button interaction and travel
- Overall ergonomics and size
At this stage CAD is about speed and exploration, not perfection. A design that looks clean on screen often behaves very differently once you build and use it.
Functional Prototyping (3D Printing)
From CAD we moved quickly into 3D printed prototypes.
This phase answers the only question that matters early on: does the mechanism actually work?
We used printed prototypes to test:
- Locking under load
- One-handed usability
- Behavior under tension versus slack
- Button feel and travel
- How the webbing interacted with the locking surface
A lot of early designs failed in predictable ways. Some slipped under load. Others bound up under tension. Some technically worked, but felt awkward or frustrating in use.
Over multiple iterations we refined clearances, locking profiles, engagement angles, and button geometry until the core function felt right.
Sourcing: Hardware, Materials, and Safety
While the mechanism was being developed, a parallel effort was happening on sourcing. This ended up being a much larger part of the project than expected.
Leash Clip Selection
One of the most important decisions in the entire product was the leash clip.
This was driven by real failure. Remie had previously come loose from two different common leash clip styles: a lobster claw style clip and a spring-loaded flap style clip. Both are common, both are easy to use, and both failed in real-world conditions.
That set the requirement very clearly: security mattered more than convenience.
We sourced and evaluated over 200 different clip designs, including lobster claws, standard leash hooks, non-locking carabiners, locking carabiners, and specialty clip mechanisms.
Most of the “easy to open” options were eliminated immediately. The final direction prioritized positive locking behavior, resistance to accidental opening, and consistent engagement under dynamic movement.
Webbing and Material Development
We also explored a wide range of leash materials:
- Fabric webbing
- PVC-coated webbing
- Polyurethane-coated webbing
- Different widths and thicknesses
- Round versus flat profiles
- Custom colors, prints, and embossing
Each had tradeoffs in durability, comfort, grip, manufacturability, and how well it worked with the locking mechanism.
We ultimately selected a webbing material that was grippy while still soft in hand, comfortable to use, compatible with the RemieLock mechanism, and resistant to marring and fraying during use.
Plastic Components and Buckles
Other components like plastic buckles and adjusters were more straightforward, but still required sourcing and validation across multiple vendors to make sure the quality and finish matched the rest of the product.
Manufacturer Selection
Once the major components were defined, we sourced full leash manufacturers and had about five different factories produce samples.
This allowed us to compare construction quality, stitching, consistency, hardware integration, and overall execution. The same design can vary significantly depending on who builds it.
Packaging Development
Packaging was also developed as part of the product. We prototyped the box in the US using Packlane to iterate quickly on size, layout, and presentation, then had the final packaging sourced through the leash manufacturer for production.
2D Drawings
Once the design was stable, we created full 2D drawings.
These drawings define the exact dimensions, tolerances, materials, finishes, and critical requirements needed for production. While many vendors will accept 3D files, drawings are still the standard for making sure manufactured parts come back correctly.
Vendor Review and Initial BOM
With drawings complete, we sent the design out for quoting and built a full BOM (Bill of Materials).
This is the point where a product stops being just a design and starts becoming a business case. The initial quote for the RemieLock mechanism came back at roughly $45 per part at a 1,000 unit MOQ.
A Quick Note on BOM Cost vs MSRP
At first glance, $45 for a small mechanical component sounds extreme. In reality, for a low-volume, non-optimized part, it is not unusual.
In consumer products there is a common rule of thumb that MSRP often needs to be roughly 4x to 5x the total landed BOM cost.
That multiple exists because the BOM is only one part of the total business:
- Manufacturing and assembly
- Packaging
- Freight, duties, and logistics
- Wholesale or retail margin
- Marketing and customer acquisition
- Returns, overhead, and profit
So if a product has a $10 to $12 landed BOM, a retail price of roughly $40 to $60 can make sense. At $45 for just the mechanism, the resulting product cost structure would have pushed the final retail price into a range that did not make sense for the market.
That is what triggered the redesign.
Cost Optimization and Redesign (DFM)
Rather than trying to negotiate pricing, we went back and redesigned the mechanism with manufacturing in mind.
We cover that process in full detail here: How To: Cost Down a Mechanical Design
The short version is that the first working design was optimized for function, then refined for CNC manufacturing, then ultimately redesigned around die casting once it became clear the CNC path would not reach the target cost.
The progression looked like this:
- Initial working design: approximately $45 per part
- CNC-optimized version: approximately $20 per part
- Initial die cast direction: approximately $5 per part
- Final DFM version: approximately $2.50 per part
The key point is that cost reduction did not come from supplier negotiation. It came from redesigning around manufacturing realities and being willing to change processes entirely when the first path hit a ceiling.
Patents
One important part of this project was starting the patent process early.
Rather than waiting until the final design, we filed around the core mechanism concepts and product variations during development. That allowed us to keep iterating, work with suppliers, and continue refining the product without exposing an entirely unprotected design.
It also made it easier to talk publicly about the project and share parts of the development process later.
Production
Once the design was finalized and the cost structure made sense, we moved directly into full production.
In an ideal world you would always have the luxury of smaller pilot runs, but in consumer products minimum order quantities often force a different decision. Once we were confident in the design and manufacturer, we committed to the full production lot.
Final Product
The final RemieLock design is not a direct evolution of the first prototype. It is the result of two distinct phases: a function-first design that proved the concept, and a manufacturing-driven redesign that made it commercially viable.
The final Sutton Slide Leash delivers:
- Secure locking under load
- Fast, intuitive adjustment
- Comfortable and durable materials
- A format that supports multiple use modes in one product
- A design that can actually be manufactured and sold at scale
You can see the final product here: RemieDog Sutton Slide Leash
Takeaway
This project is a good example of what real hardware development looks like.
It’s not just CAD. It’s not just prototyping. It’s not just sourcing. It’s not just cost reduction. It’s all of those working together.
The process looked roughly like this:
- Identify a real use problem
- Develop a new product concept instead of copying an existing one
- Use CAD and 3D printing to prove the function
- Source and test hardware, materials, and manufacturers
- Build the BOM and understand the real cost structure
- Redesign around DFM when the first solution was too expensive
- Protect the core IP
- Move into production once the design and cost aligned
Most early designs are optimized for function. Most production designs are optimized for manufacturing. Bridging that gap is the actual job.
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