Free Video Effect
Doodle Boil Effect: A Hand-Drawn Outline That Wobbles Around You
A white hand-drawn outline traces your body and keeps wobbling like 2D animation, with doodled icons on cue.
Claude Code · Opus 5.59:16Advanced
- Run the setup once
- Paste the prompt, fill in the [brackets]
- Approve the preview, get your MP4
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The prompt
effects/doodle_boil.py: add a "Doodle Boil" effect between [START S] and [END S].
- Extract my outer contour from the person mask (OpenCV findContours) and offset it 12 px outward.
- Draw this contour as a white, hand-drawn pen line:
- Thickness varying between 4 and 6 px, round caps
- A small random offset on every point (hand shake)
- The "BOIL" effect: regenerate the random offsets every 3 frames, so the line
keeps moving (like "line boil" in 2D animation). In between, the line stays still.
- The line has a slight chalk/pencil texture (irregular alpha at the edges)
- Entrance: the contour is drawn around me within 0.5 s, starting from the top of my head (stroke reveal).
- White hand-drawn icons appear next to me, following what I say:
"[WORD 1]" → [ICON 1, e.g. a clapperboard] , "[WORD 2]" → [ICON 2, e.g. a light bulb]
The icons boil with the same effect and are drawn on as they come in.
- Cool the video colors by 10% and raise the contrast a little, so the white line glows.Fill in the brackets
| Placeholder | What to put there | Example |
|---|---|---|
[START S] / [END S] | Where the effect starts and ends, in seconds from the start of input.mp4. | 12.0 / 15.0 |
[WORD 1] / [WORD 2] | The spoken words that trigger each icon. Claude finds their exact times in words.json, so they must be words you actually say. | film / idea |
[ICON 1, e.g. a clapperboard] / [ICON 2, e.g. a light bulb] | What Claude should draw as a white doodle when you say each trigger word. Simple, recognisable objects are easiest to read. | clapperboard / light bulb |
About Doodle Boil
Doodle Boil is a talking-head video effect that draws a white, hand-drawn outline around your body and redraws it every few frames so it wobbles, like the "line boil" in 2D cartoons. Doodled icons pop up next to you on words you choose. After the one-time setup, paste the prompt below into Claude Code with Opus 5.5 to render it.
Use it when: You hit a fun, energetic moment and want a moving outline and doodles to pull the viewer's eye to you.
What the Doodle Boil effect does
Doodle Boil draws a white pen line around you and never lets it sit still. The line follows your outer silhouette at a 12 px distance, varies between 4 and 6 px in thickness and has a chalky, uneven edge. Every third frame its small wobbles are re-rolled, so it shivers the way lines do in hand-drawn cartoons, while you move normally inside it.
When the effect starts, the line draws itself in from above your head and closes around you in half a second. Later, on two words you pick, small white doodles appear beside you, such as a clapperboard or a light bulb, drawn on and wobbling in the same style. The footage itself turns about 10% cooler with a little more contrast, which helps the white stroke stand out.
When it works and when it hurts
It suits energetic beats: a reveal, a joke, a quick run of ideas, the moment you introduce yourself. The outline frames you without covering anything, so it draws the eye to you even in a busy shot.
It hurts when it stays on too long or competes with other motion. A constantly moving line pulls attention, which is its job for a few seconds and a distraction over a minute. It also reads poorly on a white or very bright background, where a white line has nothing to contrast with, and during big, fast gestures, where the outline lurches around with your hands.
How Claude builds it
The person mask from the setup is the starting point. For each frame, Claude runs OpenCV’s findContours on the mask to get your outer outline as a list of points, then pushes every point 12 px outwards. Small random offsets are added to imitate a shaky hand; those offsets are generated once, kept for three frames, then replaced. That hold-then-replace rhythm is what makes the line boil instead of buzz.
The stroke is drawn with a varying width, round caps and a noisy alpha along its edges, so it looks like chalk or pencil rather than a vector path. For the entrance, only a growing share of the contour is drawn on each frame, starting at the top. The icon timings come from words.json: Claude looks up when you say each trigger word and starts that icon’s draw-on animation there. ffmpeg assembles the frames with your original audio.
Make it yours
Try a yellow or black line instead of white, a double line for a sketchier look, or a slower boil that re-rolls every four frames for a calmer feel. You can drop the colour grade if your footage is already graded, or add more trigger words and icons for a longer section. Keep the 12 px gap unless the line clips your hair, in which case widen it a little. Ask for one change at a time and compare the results side by side.
Questions
What is line boil?
In hand-drawn animation, each frame is traced again by hand, so lines never sit in exactly the same place and seem to shimmer. Animators call that line boil, and some styles keep it on purpose. This prompt imitates it by re-rolling small random offsets on the outline every three frames and holding them in between.
Can I change the line colour from white?
Yes. Ask for a different colour in the prompt, such as your brand yellow. White is the default because it stands out against most skin tones and backgrounds, especially after the cooler grade. A dark line on a dark wall disappears, so check the result before the full render.
Do I have to draw the icons myself?
No. Claude draws simple icons such as a clapperboard or a light bulb in code, as white strokes that wobble like the outline. If you want a specific symbol or your logo, put an SVG or transparent PNG in an assets folder and ask Claude to use or trace it.
Why does the outline sit 12 px away from my body?
The gap keeps the line off your skin and clothes, so it reads as a drawing around you rather than as a cut-out edge. It also hides small errors at the edge of the mask. You can ask for a tighter or wider gap; 12 px is a starting point for a 1080×1920 frame.
Step by step
Run the setup once
Open the folder that holds input.mp4 in Claude Code, choose Opus 5.5 and paste the setup prompt. The outline Claude draws comes straight from the person mask the setup creates.
Pick two trigger words
Find two words in your section that suit a simple icon, such as 'film' for a clapperboard or 'idea' for a light bulb. They have to be words you say out loud.
Paste and fill in the prompt
Copy the Doodle Boil prompt, replace the start and end seconds, the two trigger words and the two icons, and send it.
Check the boil at full speed
Watch the outline at normal speed, not frame by frame. If it buzzes instead of wobbling, or snags on your hair, give one note and re-render that range.
You need: Setup prompt (run once) · Person mask · Word timestamps · Two trigger words
Tips
- Fatih Türkmen, who wrote the original prompts, counts Doodle Boil among the most attention-grabbing effects in the set. That is his taste, and it is also a good reason to use it for a few seconds rather than a whole video.
- Pick trigger words that are concrete nouns you say clearly. Claude looks them up in words.json, so a word you only imply will not trigger an icon.
- A plain background and some space between you and the wall give the cleanest contour. Loose hair and fast gestures make the outline jump in a way that is not the intended boil.
- The original prompt has no preview line. Add 'Render a 2-second preview first' at the end if you want to check the line weight before the full render.
If it goes wrong
The outline buzzes on every frame instead of wobbling every third frame.
Small changes in the mask are moving the contour each frame. Ask Claude to smooth the contour over time and simplify its points, while still re-rolling the hand-tremor offsets only every 3 frames.
The line looks like a clean vector stroke rather than a pen.
Ask for more variation in thickness within the 4–6 px range and a rougher, irregular alpha along the edges, then check one frame zoomed in before re-rendering.
An icon appears at the wrong moment or not at all.
Ask Claude to print the timestamp it found for each trigger word in words.json. If the word was transcribed differently, use the spelling in the transcript.
What it does not do
- The outline is only as good as the person mask. Flyaway hair, a fast hand or clothing close to your background colour make the contour jump.
- findContours with an outer contour traces your silhouette only, so the line does not follow inner shapes such as an arm crossed in front of your chest.
- The cooler, higher-contrast grade covers the whole frame during the effect, so cutting in and out of it can show a colour jump unless Claude eases the grade in and out.
- The icons are drawn in code as simple line drawings. A detailed or brand-specific icon is better supplied as your own SVG or transparent PNG.
Sources
- Robust Video Matting (RVM) — GitHub — PeterL1n. Accessed October 21, 2026.
- Image segmentation guide — Google AI Edge — MediaPipe. Accessed October 21, 2026.
- faster-whisper — GitHub — SYSTRAN. Accessed October 21, 2026.
- Claude Code overview — Anthropic. Accessed October 21, 2026.
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