Case study · AI-directed build

Anyone can prompt a picture of a house. This one has a floor plan.

Jason Ensor directed Claude Code to design, build, render and film a 335 m² lake house in four days. Every wall, chair and tree is Python. You can measure it, walk through it in a browser and take it apart. This case study shows how the work was directed, and the system that let one person direct it.

Type: AI-directed 3D build
Directed by: Jason Ensor, PRTOTYPE.COM
Built by: Claude Code with Blender 5.2
Dates: 31 Oct – 3 Nov 2026
Status: Prototype · 3D model online

Days: 4; Saturday 31 October to Tuesday 3 November
Messages from the director: 26; Most of them one line. Each one a decision
Lines of Python: 4,547; Fourteen scripts generate the whole scene
Objects modelled by hand: 0; Every mesh comes out of a script
Credits, each approved: 129.5; Priced and tested before every spend

01The brief

One line and a reference.

The brief was a single message: an American-style house in Blender, one level, a lake outside, current architecture, full detail. It ended with two words.

Plan. Go.Nothing was built until the plan was agreed.

Jason attached the reference himself: Urban Decoders' test of AI 3D modelling, which builds a villa by writing the plan first, then a script that drives Blender with no window open, then checking the renders. The lake house keeps that method and changes the building: steep black standing-seam gables, board-and-batten cladding and a glass-gabled great room facing the water.

Claude replied with a design on paper before any code: concept, dimensions, a room schedule with areas and a site plan. Jason read it and answered “Yes, write it.” Those numbers became plan.py, the one file that defines every wall, opening and room.

Orthographic floor plan of the house with labelled rooms and areas — **Plan** · Rendered straight from the model, cut at 1.6 m. Rooms, areas and the scale bar come from the same numbers as the walls.

Area: 335 m² (about 3,600 sq ft) conditioned
Rooms: 3 bedrooms, 2.5 baths and an office
Massing: Tall glass-gabled pavilion between two lower gabled wings
Roofs: 6:12 wings, 8:12 pavilion, vault 7.7 m at the ridge
Outside: Breezeway garage, covered lake porch, deck, dock and canoe
Site: Lawn falling to a pebble shore, far shore 155 m away

02The director

Twenty-six messages, each one a decision.

Read in order, the messages that steered the build are a design review. They raise the bar, reject what isn't working, add what is missing, and refuse to pay for anything that hasn't been tested.

Sat 31 OctRaise the bar
“Go do the 3D render of the house in detail, including furniture and elements. Attention to detail.”
Every room furnished, down to drapes, duvets, lathed vases and 1,350 trees. Twelve Cycles renders at 1920 × 1080.
Sat 31 OctRedirect
“This needs to be in 3D.”
Pictures were not the deliverable. The scene became a compressed glTF model in a three.js viewer that anyone can walk through in a browser.
Sun 1 NovAdd
“Do a walkaround showcase button.”
“Let's build a deconstruction of the house.”
A guided walkaround, then a take-apart view that lifts the house into seven labelled layers, slab to roof.
Sun 1 NovDirect
“Everything constructed from just the ground and dock, appearing over 30 seconds, with a zoom around, then the walkthrough.”
The build-from-ground sequence that now opens the film: bare grass, slab, walls, trees growing outward, roofs, then eye level.
Mon 2 NovReview
“What could we do to improve this?”
“I agree with all. Plan the work and start.”
Review before more building. Claude listed the improvements as a written plan; Jason approved it whole. Seven feature commits followed, among them sky and time of day, a reflecting lake, surface hotspots, a floor-plan minimap, touch walking, VR and baked textures.
Tue 3 NovPreview first
“Cut the video to a 30-second run. Build it in Blender and show me first.”
A free Blender cut to judge before any paid generation was considered.
Tue 3 NovCritique
“It goes round twice. Cut one revolution, put in a boat and some water ripples, and improve the trees.”
One orbit instead of two, a boat moving on the lake with its wake, ripples on the water and fuller trees.
Tue 3 NovPrice it
“What would it cost in credits to make this photorealistic? Which model? Give me my options.”
Free quotes for every model before a credit moved. Making the whole film photoreal at 1080p came to about 126 credits.
Tue 3 NovStage the spend
“Test aerial.”
“Run the 30 s at 480 to iron out the issues.”
“Yes, 1080p.”
One shot for 5 credits, the whole film at 480p for 36, a 10-credit re-run of the construction shot after a stray roof appeared in the sky, then the outdoor shots at 1080p for 52.5. The finished film cost 103.5 credits including every test, below the 126 quoted for one blind pass.

Quotes are Jason's own messages from the session logs, with spelling tidied. The other ten are approvals, requests to see the work, and requests for links.

03The system

The system behind the direction.

One-line messages only work when the agent already knows the rules. Jason built that operating system before this project began. It is the reason one person could run four sessions at once and still sign off every step that mattered.

117

Skills in the toolkit

jay-fleet, Jason's own plugin for Claude Code: done gates, audits, review boards, and research and video workflows, with 20 subagents they dispatch. This build used video-research to take the method from the reference video and higgsfield-video to price and run every generation.

Written by Jason · 110 commits since June 2026

105

Project pages in memory

ClaudeOS keeps a page per project, a decisions log and a ledger of open placeholders, so each session starts from what the last one knew instead of searching for it.

Read at the start of every session

House rules

Plan before building
Check before saying “done”
Commit locally at every checkpoint
No credit spent without a yes
British English, full file paths

Sessions in parallel

While the main session built the viewer, three more ran alongside it: the film, the photoreal stills and a check for Unreal Engine. Each had its own brief and its own files, so none could overwrite another.

Started by Jason from Claude's proposals

How a request moves through it

JasonBriefOne line and a reference
Gate · JasonApprove the planA design on paper before any code
ClaudeBuildPython drives Blender with no window open
ClaudeRender and checkLooks at its own frames and fixes the code
JasonReviewRaise the bar, redirect, add
ClaudePrice and testFree quotes, then the cheapest test first
Gate · JasonApprove the spendNo credit without a yes
ClaudeCommit and recordA local commit and notes for the next session

Jason directsClaude buildsApproval gate

It is the same discipline PRTOTYPE.COM applies to client software: a written specification before the build, checks before anything is called done, and a person signing off every step that costs money or can't be undone.

04The house

What the method produced.

01 / The 3D model

Walk it, light it, take it apart.

The Blender scene is exported to a compressed glTF model and opened in a three.js viewer that Claude wrote and published.

Seven labelled layers that lift off from slab to roof
A showcase that builds the house from bare ground, then walks through the doorways
Sun from morning to dusk, with the lamps and the fire coming on
Click any surface for its material; floor-plan minimap; finish swatches
Walk with W A S D or a thumb pad, or in a VR headset

three.js 0.160glTF + DracoWebXR

The house lifted into stacked layers above its site in the browser viewer — **Take apart** · Seven layers, roof lifted first.

The house at dusk from the dock with warm interior lights — **7:50 pm** · The lamps come on as the sun drops.

The viewer's control panel beside an interior view of the great room — **The viewer** · Views, time of day, swatches, minimap.

Overhead view with the roof removed, showing furnished rooms — **Roof off** · Every room, furnished.

02 / The film

Thirty seconds, grass to house.

A second script turns the showcase into a Blender camera path and renders it frame by frame. The house rises from bare terrain, the trees grow outward from it, and the camera spirals down to eye level before visiting seven rooms. The outdoor shots then went through Wan 3.0 on Higgsfield; the interiors stayed as Cycles renders because the restyle made them greyer.

Blender camera pathWan 3.0ffmpeg

Side by side · The Blender cut and the photoreal version of the same 30 seconds.

Render or photograph? Drag to compare.

Photoreal restyle of the same view, from the dock

Blender renderPhotoreal restyle

Stills restyled with Nano Banana Pro after four models were priced, under a 30-credit cap: 26 spent. Roof colours had to be named or they came back silver. The Cycles render stays the reference for anything dimensional.

All twelve renders

The house from the end of the dock — **From the dock** · Low sun, south-west

Aerial view over the lake — **Aerial** · Clearing, dock and forest

Front of the house with the entry portico — **Entry court** · Morning sun

Dollhouse cutaway of every room — **Cutaway** · Roof and ceilings off

Great room interior — **Great room** · Vault and fireplace

Kitchen with sage cabinets — **Kitchen** · Sage shaker, waterfall island

Dining room — **Dining** · Trestle table, linear chandelier

Foyer looking through to the lake — **Foyer** · Front door to the lake

Primary bedroom — **Primary suite** · Tufted bed, linen drapes

Primary bathroom — **Primary bath** · Oval tub, marble floor

Covered lake porch — **Lake porch** · Swing and lantern

Floor plan — **Plan** · Labelled rooms and areas

The build, in five frames

Bare grass clearing by the lake — **0.4 s** · Bare ground and dock

Concrete slab appears on the clearing — **1.3 s** · Slab

Walls and furniture rising on the slab — **2.4 s** · Walls and rooms

House shell with trees growing around it — **4.6 s** · Shell, glazing, trees

Finished house from the lawn at eye level — **9.6 s** · Roofs on, eye level

05Claude's part

A builder that checks its own work.

Claude Code wrote every line: a small mesh toolkit for Blender, the house in layers, a 1,030-line browser viewer and the film scripts. After each change it rendered test frames, looked at them and traced what was wrong back to the code.

Script	What it builds	Lines
plan.py	Every dimension, wall, opening and room	140
kit.py	Mesh builder: rounded boxes, drapes, lathed vessels	382
shell.py	Slab, walls, glazing, roofs, porch, chimney	422
interior.py	Doors, kitchen, fireplace, every room's furniture	877
furniture.py	Sofas, beds, lamps, plants, curtains	443
materials.py	Procedural materials: oak, marble, bouclé, zellige	590
landscape.py	Terrain, lake, dock, canoe, rocks, 1,350 trees	443
cameras.py	Sky, sun, render settings and the twelve shots	175

Some of what it caught

Walls on the lawn. Every interior wall came out rotated 90°: two tables used opposite axis conventions.
Pale grey hills. Distant terrain mirrored the sky at grazing angles, so its reflectivity was turned down.
White panels in the glass. Ceiling lights showed as reflections in the glazing until they were hidden from reflections.
Pink ground. In the browser model a hidden mask was exported as colour and the lawn turned salmon.
A roof in the sky. The 480p film test showed a stray roof floating behind the house; the shot was re-run in two halves.

06Limits

What still falls short.

The trees are placeholders.They are stylised cones and blobs. The photoreal pass replaces them up close, but from the air they stay low-poly. Real tree assets in Blender would fix it; more prompting won't.
The restyle invents details.It redesigned the shower in the primary bath and darkened a door. The Blender renders stay the reference for anything dimensional.
The browser model's lighting is live, not baked.Materials are baked into small textures, but light and shadow are calculated in the browser, so the model reads flatter than the renders.
No Unreal walkthrough yet.The third step of the reference method is blocked: Unreal Engine isn't installed on this machine, and the session that checked stopped there rather than install it.