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.
Fast concepts make the next decision clearer. When a rough look and cost model take an afternoon, fewer ideas die as vague briefs, and the ones that reach a physical prototype need a better reason than novelty.