The Add-in Libraries window contains available add-ins, which you can browse and add to the Model Builder by selecting the check box for the add-in and then click Done. This way, you enable the add-in so that it becomes available from the Add-ins menu. When you choose the add-in from that menu, it is imported and the selected form is added or a selected method is run. You can also make add-ins available by importing them without adding any form or running any methods. To do so, right-click an add-in and choose Import Add-in. Imported add-ins are also available from the Add-ins menu. If the add-in includes documentation, click the Open PDF Document button underneath the add-in description, or right-click the add-in and choose Open PDF Document.

Click the Refresh button () to update the list of add-ins. You can also add separate user-defined add-in libraries (see below).

The following settings can be modified using the buttons at the bottom of the Add-in Libraries tree on the Add-in Libraries page in The Preferences Dialog Box and — if the Allow managing libraries in the Add-in Libraries window check box on that page is selected (the default) — also in the Add-in Libraries window itself.

Click the Add User Add-in Library button () to add customized folders. In the Add User Add-in Library dialog box, navigate to a location on your computer and select an existing directory or click Make New Folder to create a custom folder. Click OK to save the changes and exit, or Cancel to exit without saving. The user-defined add-in library appears alongside the built-in add-in libraries,

Optionally, you can replace the standard folder icon () with custom icons of your choice that reflect the content of your library folders. To use a custom icon for a folder, create a PNG-file with an image size of 16-by-16 pixels and save it in the folder under the name folder.png.

Click the Set COMSOL Add-in Libraries Root Directory button () to edit or set the root folder. This redirects the COMSOL software to a different folder where customized add-ins can be stored.

In the Set COMSOL Add-in Libraries Root Directory dialog box, navigate to the new root folder location or click Make New Folder. Click OK to save the changes and exit, or Cancel to exit without saving.

This button is enabled after a user add-in library folder has been created. Select a user add-in library root folder in the Add-in libraries tree and then the click the Remove Selected () button to remove the library from the tree.