A modular rotational grip trainer — crush, rotation, and thick-grip in one desk-sized device. This is the build journal: what's real, what's only rendered, and what's still in my head.
I have a Spartan race in September, and in obstacle racing grip is what fails first. Monkey bars, multi-rig, rope climbs, sandbag hauls — every obstacle runs through your forearms. You can have the cardio of a triathlete and still fail because you couldn't hold on for fifteen more seconds.
I've collected the usual grip gear — Captains of Crush grippers, a twister bar, Fat Gripz, a wrist roller. Each trains one dimension, they're scattered around the house, and I don't reach for any of them often enough to matter.
So I started exploring — not building yet, just pressure-testing the idea before committing any plastic to it.
I described the device in plain English — ab-wheel form factor, a central disc housing the resistance, two bars, swappable grip sleeves — and pushed on two questions: does this already exist? and what mechanism would actually work?
Four candidate mechanisms came out of it — torsion spring, friction disc, magnetic eddy current, viscous fluid damper — ranked by manufacturability against feel. The closest existing product is The Burn Machine; nothing combines all three modalities in one compact device.
Four renders, each for a different job — a hero shot, an exploded view, a blueprint, and a use-case triptych.
The blueprint is the one to be honest about: it's not a real engineering drawing, it's a render that looks like one. The dimensions are internally consistent enough to brief a manufacturer — but no real CAD exists yet.
Before getting attached, I sanity-checked the market. Grip strengtheners are about $812M globally at a 5.4% CAGR, ~$153M in North America, with online retail roughly 40% of sales.
Real but small — not a unicorn, not a wasteland. The kind of niche a well-positioned product can hold without needing to be a hit. Good enough to keep going.
I priced the prototype path. Adam CAD turns text into parametric models and print-ready STLs; Zoo Design Studio is more capable but steeper. Either gets me from description to printable part.
The plan: model each part (disc shell halves, grip sleeves, axle), print them, source the spring and bearings from McMaster-Carr, and assemble v1 for under $35 in materials.
I also drafted a 16-slide Kickstarter deck — problem, solution, market, unit economics, competition, manufacturing, use of funds — with real estimates and assumptions flagged.
Not because I'm launching tomorrow, but because drafting it forces the unit-economics math early and exposes exactly which costs still need real quotes.
This is on my portfolio because it's an honest snapshot of how I scope an idea before committing to it: get to a render, a market check, and a BOM fast enough that the only thing left to decide is whether it's worth building.
Cheap concepts change the bar. When "here's what it'd look like and cost" takes an afternoon, fewer ideas die at the brief stage — and the ones that move to a physical prototype have to earn it on conviction, not novelty.