Describe the first draft
Connect a compatible AI assistant through MCP and describe the characters, setting and action. Or start by arranging the scene yourself in your browser.
3D SCENE BUILDER FOR AI VIDEO
Describe your scene.
AI builds. You direct.
Let your connected AI assistant build an editable 3D scene. Refine camera angles, character movement and timing by hand, then export a reference for your AI video generator.
Free beta. No credit card required. Sign in with Google to save your scenes. External AI generation is separate.
In your browser · Desktop editor · Bring your own AI
YOUR SCENE. A NEW PICTURE.
Set the scene.
Reveal the difference.
A Reelpen scene on one side. The AI video made from it on the other. Drag the line to compare the same moment.
REELPEN
AI RESULT
Drag to compare
01 / SOHO
FROM IDEA TO AI VIDEO
Three simple steps to your next scene.
Direct the details
Adjust the camera angle, edit the movement path and refine the timing in the same 3D scene. Preview the shot and ask your assistant for another change whenever you need one.
Create with your AI video generator
Export your reference video and keyframes. Use the inputs your generator supports to create the final look and style.
YOUR IDEA. YOUR SCENE.
Make your next shot easy to explain.
Turn the scene in your head into a reference you can see, adjust and bring to your AI video workflow.
Start with ready-made objects
Build with characters, vehicles and environment pieces. Arrange the scene and focus on the shot you want.
See the camera's view
Follow a character, frame a close-up or move through the scene. Check the camera preview while you work.
Bring your scene to your workflow
Keep the placement, movement and framing in your reference. Choose the visual style in your AI video generator.
Before you build your first scene
Is Reelpen free?
The current beta is free and requires no payment method. See beta access and storage limits. External AI video services have their own charges.
Does Reelpen generate the final AI video?
Reelpen builds editable 3D scenes, camera shots and motion references. Export video or PNG frames, then use a video service that supports those inputs to create the final appearance.
Can AI build a scene that I can edit myself?
Yes. A compatible AI assistant connected through MCP can arrange objects and direct motion and cameras in the scene you allow. You can then refine the result in Reelpen's editor. The assistant is a separate service; follow the AI connection guide before asking it to build.
What can I plan?
Character routes, turns and sit–stand actions; prop placement; and camera framing and movement. Start with one shot and preview it before exporting. Read the character motion guide.
Do I need to install 3D software?
The editor runs in your desktop browser. Sign in to save projects. Your scene stays editable, so you can refine a reference without rebuilding the shot.
BUILD WITH YOUR AI ASSISTANT
Describe a shot. Direct it in Reelpen.
Connect Claude or Codex to arrange scenes, direct motion and cameras, and organize film boards.
LEARN THE WORKFLOW
Plan your next AI video scene.
Build a character motion reference for AI video
Make walking, turns and sit–stand timing visible before generation.
Read the guide →Reference video or keyframes: what to export for AI video
Choose the output that explains your shot and your model accepts.
Read the guide →Connect Claude or Codex to Reelpen
Describe the shot. Let your AI work in your editable 3D scene.
Read the guide →How to build a scene for AI video
Ask AI for a first draft, then refine the 3D scene yourself.
Read the guide →Create a camera motion reference for AI video
Plan a moving shot and keep its subject in frame.
Read the guide →Use 3D storyboarding to plan an AI video shot
Make blocking and camera angles clear before generation.
Read the guide →Your next AI video starts here.
Start with one character, one path and one camera.