Revit plugin
Molding uses a two-step flow: you design the family in the browser editor, then a Revit add-in reads the design and generates the .rfa.
Download and install
- Download the latest Molding installer (
.msi) from the project releases. - Close Revit if it is open, then run the installer.
- Restart Revit. Molding appears in the Add-Ins ribbon tab.
Supported versions: Revit 2021 and newer.
Opening the editor inside Revit
Click Molding in the Add-Ins ribbon. The same editor you use in the browser opens as a panel inside Revit β same interface, same files, same JSON. You can load any family you designed online by copying its JSON file into the panel.
In panel mode the interface switches to a tabbed layout:
| Tab | Contents |
|---|---|
| Design | The 3D viewport + the Parameters / Types / Generators editor panel |
| Catalog | Browse and place pre-built shared families. Export All⦠batch-generates every catalog family as .rfa files to a local folder. |
Toolbar buttons
| Button | When it is enabled | What it does |
|---|---|---|
βΆ Generate | Running inside Revit and a family is open | Creates or re-creates the .rfa via the Revit Family API |
β» Update | Inside Revit and design has changed since last Generate | Re-generates the .rfa (skips if nothing has changed since last Generate) |
πΎ Save | Always | Downloads the family design as a .json file |
π New | Always | Starts a new family from a template |
End-to-end workflow
- Design β open or build a family in the browser or in the Revit panel.
- Generate β click
βΆ Generate. Molding creates the.rfaand opens it in the Revit Family Editor in the background. - Load into a project β in Revit, load the
.rfafrom the Family Editor, or use Load into Project. Place it like any Revit family. - Edit β change parameters or geometry in Molding, then click
β» Updateto push the changes. The.rfais rebuilt without losing any project placements.
The generated family is fully parametric: Revit's own solver handles recomputation when parameters change. No Molding plugin is needed at runtime β only at generation time.
The generated .rfa
Molding generates the full constraint apparatus for you:
- Reference planes β one per unique parametric coordinate axis.
- Dimensions β labelled and associated to their parameters.
- Family parameters β fully wired so Revit's solver flexes the geometry.
The Family Editor file will be dense (many planes and dimensions), but nobody reads it. The Molding node graph is the design surface; the .rfa is a generated artifact.
Saving and loading JSON
πΎ Saveexports the family as a.jsonfile you can share or check into version control.- To reload: click the models icon (grid) in the toolbar β choose a saved model. You can also open a family from the Catalog panel.
- Families in the public catalog can be forked (click the fork icon on a catalog card) and customised as your own.
Troubleshooting
Generate button is greyed out β the panel is open in the browser, not inside Revit. The Generate button is only active when Molding is running as a Revit panel.
"Unknown parameter" error β a node field references a parameter key that does not exist. Check the Parameters tab for typos; the red row in the Generators list shows which field.
Geometry looks wrong in the preview but correct in the .rfa (or vice versa) β the web preview and Revit each evaluate the same JSON, but the preview is approximate for some forms (revolution, sweep). The .rfa is authoritative.
Flexing fails after load β check that the family parameters in Revit's Manage β Family Types panel match the parameter keys in Molding. If you renamed a parameter, re-generate rather than update.