I spent $17 last night finding out which model should animate the Roadster Elon just unveiled. $2 of it was Kimi K3.1 Pro. $15 was Opus 5.5. The $2 render is the one I kept.
Same prompt, same six steps, 160K tokens against 600K.
My rule for anything 3D: never ask for "an animation of the Roadster". One piece per prompt.
Step 1 -> Three.js scene, camera, a dark pad.
Step 2 -> The Roadster as a parametric model: body, wheels, glass, lights.
Step 3 -> The launch structure: vertical ramp, scaffolding, clamps. Opus started burning tokens here. Kimi just built it.
Step 4 -> The sequence: clamps release, tilt up the ramp, thrusters ignite, lift-off with exhaust and camera shake.
Step 5 -> Lighting last: headlights, thruster glow, fog.
Step 6 -> Each model reviews its own render and fixes its own timing.
My mistake, and it cost real money: on the first Opus run I let it light the scene in step 2. It spent 180K tokens on headlights bright enough to interrogate God and never reached the ramp. Reran in the right order. Still $15, still no thrusters.
The split:
> Three.js: scene, camera, ramp.
> GLSL and tweens: every line by the models.
> Kimi K3.1 Pro: launch structure, ramp, thrusters that fire.
> Opus 5.5: a car and a very expensive flashlight.
> Me: play both, keep one.
Where I landed: for scene work I now default to Kimi on the high-speed version. Seconds per step, $2 against $15, roughly 7x cheaper for the better animation.
Commit after every step that works. A bad prompt should cost seconds, not fifteen dollars.