When someone picks up a CoinConnex case and slides in a slab that fits perfectly, with no wobble and no binding, they are feeling the result of a process that started months earlier with a pair of digital calipers and a pile of coin slabs from four different grading services.
Before we draw a single line in CAD, we measure. Not one slab, dozens of them: NGC slabs from different years, PCGS slabs in various denominations, CAC holders, ANACS holders. We measure width, height, thickness, corner radius, and the position of any protrusions like label tabs or holder clips.
Why so many? Because grading services update their holders over time. An NGC slab from 2015 might differ slightly from one made in 2024, and PCGS has changed its holder design multiple times. If we only measured one slab from each service, our case might fit new slabs perfectly and old ones poorly, or the other way around.
Every measurement goes into a spreadsheet with min, max, and average values. The case design targets the averages but must clear the maximums. A case that fits the average slab but not the largest one is a failed design.
We use Fusion 360 for all product design. Every case starts as a parametric model, meaning the dimensions are driven by variables (slab width, slab height, slab thickness, wall thickness, clearance) rather than hardcoded numbers. If a grading service releases a slightly different holder, we update one variable and the entire model adjusts.
The channel profile is the critical feature. It is not just a rectangular slot. It has a slight draft angle for easy insertion, a relief at the bottom for slab tabs, and a width that balances snugness against ease of use. Too tight and the slab is hard to insert. Too loose and it rattles. The sweet spot is a fraction of a millimeter of clearance per side.
Lid mechanisms, stacking geometry, and label areas are all designed as separate components that reference the same base parameters. A 5-slab case and a 20-slab case share the same channel profile, the same lid track, and the same stacking interface. They just differ in length.
The first print of a new design is never the final one. We print a test piece and immediately start fitting real slabs. Does the NGC slab, the tallest and thickest of the standard holders, slide in smoothly? Does the wider PCGS slab clear the channel without binding? Does the smaller ANACS slab sit without wobble? Does the lid slide freely but stay closed when the case is inverted?
We typically go through 8–15 prototype iterations for a new product. Each iteration changes one or two variables: widen the channel by 0.1mm, deepen the lid track by 0.2mm, add 0.5mm to the stacking recess. Small changes, tested one at a time, until every slab from every service fits correctly.
This is where 3D printing is essential. Each prototype takes 1–3 hours to print, so we can test several iterations in a single day. In injection molding, each iteration would take weeks and cost thousands of dollars in mold modifications.
Once the fit is right, we test durability. Cases are filled with slabs and dropped from table height onto concrete. Lids are opened and closed hundreds of times to check for wear. Cases are stacked ten high with full loads to verify the interlocking geometry holds. Cases sit in a hot car in the workshop parking lot in summer to confirm the PETG versions do not deform.
If anything fails, we go back to Step 2 and adjust. A lid that loosens after a hundred cycles gets a redesigned track. A stacking interface that shifts under load gets deeper engagement features.
The final step before a product goes live is dialing in the production print settings: layer height, print speed, temperature, infill pattern, and wall count. These affect dimensional accuracy, surface finish, strength, and print time. We run test batches with different settings and measure the output to find the right balance.
Every production print uses the same validated settings, because the case you receive should be identical to the one we tested.
It is a lot of work for what looks like a simple plastic case. All of it exists so that the one thing you actually feel, the fit, is right every time.