TrackWright

What was the problem?

Carrera Digital slot-car racers design their layouts the way modelers always have: on graph paper, in spreadsheets, or by dry-fitting real track on the living-room floor. None of those methods tell you, before you buy anything, whether a design actually closes into a loop, whether it physically fits the space you have, or exactly which numbered Carrera pieces — and how many of each — you need to build it. The result is over-ordering, under-ordering, and a lot of trial and error with real plastic track. There was no tool built specifically for the Carrera Digital 124/132 catalog that let a hobbyist design first and shop second.

How did we approach it?

We didn't start with a page builder — we started with the geometry. The core of TrackWright is track-geometry, a framework-agnostic TypeScript engine (39 source modules, 78 test files) that is the single source of truth for every surface of the app: closed-loop detection and relaxation, banking-aware collision detection, elevation and ramp balancing, lane-change joinery, pit lanes, and support-leg placement. Every view — the 2D editor, the 3D viewport, and the parts list — reads from that one model, so nothing can drift out of sync between what you draw and what you build. On top of that engine, we built a single Three.js scene with two swappable cameras: an orthographic camera for a pixel-perfect 2D view synced to an SVG layer, and a perspective camera for real-time 3D orbit, pan, and zoom. Because both views share one geometry, what you lay out top-down is exactly what you see when you orbit around it in 3D — including procedurally generated asphalt, banking, shoulders, elevation, and support legs, colored from real Carrera product photography. We shipped it as a Rails 8 app with the modern Rails stack end to end — Solid Queue, Solid Cache, Solid Cable, Hotwire, ViewComponent, Kamal to a self-hosted Hetzner box — and layered a client-side SQLite WASM store on top so the planner works fully offline as a PWA. Auth is passwordless-first (WebAuthn/passkeys, TOTP, email OTP), matching a product built for people who don't want to manage another password.

What did we deliver?

What was the outcome?

TrackWright is live in beta today, invite-gated while we grow the catalog and harden the generator. Early builders are using it to plan real Carrera Digital 124/132 layouts and shop against an exact, priced parts list instead of guessing — the core loop the product was built to prove out. 325 builders have signed up so far, with 423 of the 515 saved layouts built out beyond the starter template — real design work, not just account creation. 32 people have had their beta access approved.