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Pour individual golden grains through a narrow glass neck and watch them collide and form a lower pile. Circular grains move under gravity and collide through positional contact constraints. A curved hourglass boundary narrows their path, while tangential damping reduces sliding at grain contacts. The pile is formed by the moving particles rather than a pre-drawn fill mask. Reuse supplied assets or quote new media through PopNow.

Uses PopNow for
Music & voice
Needs
Python 3 · FFmpeg

Generation is optional when you have suitable input material.

v1.0.0 · Updated Oct 25, 2026 · 1.1 MB · Use it for personal and client work; please don't resell or share the package.

What you get

  1. An editable 8-second 720p sample and local MP4 renderer, silent.

  2. The container, particle contacts and material presentation are coordinated. Changing neck width changes which grains can pass and how the lower pile develops, instead of merely stretching an animation.

  3. A six-frame contact sheet, render receipt and input self-check.

Good for

  • Tactile time-passage motion studies
  • Comparing granular flow through different passage widths

Not for

  • The grains are two-dimensional circles with simplified contact friction. This is a visual study, not a calibrated granular-material solver; some narrow settings can jam.

How it works

Includes a local renderer

  1. Choose the material

    No image is required. The wooden stand, glass boundary and individual grains are procedural.

  2. Shape the motion

    Edit the documented project controls, then validate the exact settings. Grain count from 180 to 900 controls the requested number of particles, subject to initial container capacity.

  3. Render and review

    Export locally to MP4, inspect the contact sheet and watch the whole film. Check that the main part of the film contains visible transfer through the neck, that the pile develops through contact and that no grains escape the glass.

How the workflow runs

How Hourglass Granular World works

Circular grains move under gravity and collide through positional contact constraints. A curved hourglass boundary narrows their path, while tangential damping reduces sliding at grain contacts. The pile is formed by the moving particles rather than a pre-drawn fill mask.

What's inside the skill

What you can change

  • Grain count from 180 to 900 controls the requested number of particles, subject to initial container capacity.
  • Neck width from 8 to 40 changes the passage size.
  • Gravity from 250 to 1,300 changes particle acceleration.
  • The seed changes the initial arrangement and grain tones.

What to review before delivery

  • The local self-check compares three frame samples after a meaningful input change and rejects its documented invalid case.
  • Output protection rejects overlap with input files and preserves existing sidecars unless overwrite is explicit.
  • Check that the main part of the film contains visible transfer through the neck, that the pile develops through contact and that no grains escape the glass. This final visual review is manual.

See the package files

These are selected working files from this edition, with their actual role. The complete download also contains instructions and applicable license notices.

  • The task-specific motion mechanism and supported inputs.

    scripts/scene.py

  • Protected MP4 export, contact sheet and hash receipt.

    scripts/runtime.py

  • Editable settings used by the supplied sample.

    examples/project.json

  • Actual changed-frame, invalid-input and output-protection checks.

    scripts/selftest.py

  • Input ranges, material placement and honest limits.

    references/inputs.md

Why use this skill

Start with this package

The container, particle contacts and material presentation are coordinated. Changing neck width changes which grains can pass and how the lower pile develops, instead of merely stretching an animation.

What PopNow adds

Use PopNow for the missing Music & voice in this workflow. Keep adequate material you already own, then bring new assets back into the editing and assembly steps described here.

Compare the options

A prompt, your own skill, or this workflow?

Start with a prompt

Your agent can create from a plain request. The brief, visual rules, asset choices, output format and review process still need to be established for that project.

Write your own skill

You choose and maintain the reusable instructions, defaults, file structure and checks. This is useful when your process needs different rules or integrations.

A workflow created for PopNow

This workflow was built for PopNow. Its source files, included dependencies and applicable notices are part of the package; the scope described below belongs to this edition.

Guide reviewed Oct 25, 2026

What will this cost?

The hourglass and grains are rendered locally without generated assets. Optional music or sand-like sound effects can be quoted through PopNow or supplied by the user.

Generation is optional when you have suitable input material. Free skill. New media is quoted before it runs.

The skill package

Free to install under your account's download allowance. The package license covers your own and client work; redistribution is excluded.

Existing assets and local work

Reusing suitable assets, editing files and running local assembly do not call a PopNow generation model. Your computer and any required runtime still do the work.

New AI images, clips or sound

Quoted for the actual model, inputs, count, duration and resolution. Extra alternatives, revisions or optional enhancement passes can add generation requests.

Your agent and hosting

Any subscription, hosted computer, deployment or other provider fee belongs to that service. Installing this skill does not include those services.

Check the cost of your version first

Your assistant can inspect the available models and quote the exact request first. You choose which optional passes to include and approve spending before generation.

Ask your assistant

  • Use the PopNow skill "Hourglass Granular World" for my project. List the inputs you can reuse, quote only the missing media, show the quoted total and flag any unpriced steps. Separate optional enhancements, and wait for my approval before starting anything paid.

How PopNow billing works

Connections using a PopNow API key, including API-key MCP connections, spend from the separate API balance in USD. A ChatGPT or Claude connection authorized through OAuth spends website credits. These balances are separate; the quote shown by your connection is the approval basis.

Download allowances and current account conditions apply. A free package does not mean unlimited free generation.

See model ratesAPI USD balanceWebsite credit packs

How to use it

You say

  • Use the PopNow skill "Hourglass Granular World" (hourglass-granular-world) for this: Render the supplied 8-second example. Make a second version with neck_width set to 20. Show the changed motion and quote any missing media before generation.

Then try

  • Show how the changed setting affects the actual motion.

  • Keep my adequate source material and prepare an optional soundtrack quote.

What to have ready

  • No image is required. The wooden stand, glass boundary and individual grains are procedural.
  • Python 3, Pillow, NumPy, FFmpeg and ffprobe
  • The project controls listed in the input contract

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Questions

Is the lower pile a changing image mask?

No. It consists of the same individual grains that pass through the neck and resolve contacts below.

Why can a narrow neck jam?

The simplified circular grains can form contacts that obstruct the opening. Widen the neck or change the initial seed if the intended film needs continuous flow.

Can I use it for engineering calculations?

No. The contact model and friction are simplified for an artistic two-dimensional animation and are not calibrated against a real material.

What is already packaged in Hourglass Granular World?

The task-specific motion mechanism and supported inputs. Protected MP4 export, contact sheet and hash receipt. Editable settings used by the supplied sample. Actual changed-frame, invalid-input and output-protection checks. Input ranges, material placement and honest limits.

Which parts of Hourglass Granular World can add a charge?

The hourglass and grains are rendered locally without generated assets. Optional music or sand-like sound effects can be quoted through PopNow or supplied by the user. Connections using a PopNow API key, including API-key MCP connections, spend from the separate API balance in USD. A ChatGPT or Claude connection authorized through OAuth spends website credits. These balances are separate; the quote shown by your connection is the approval basis.

How does Hourglass Granular World differ from writing a prompt or my own skill?

The container, particle contacts and material presentation are coordinated. Changing neck width changes which grains can pass and how the lower pile develops, instead of merely stretching an animation.