Using 3DM (Rhino) content can be a great tool in building up a custom library. Follow the steps in either method below to convert 3DM content into GDL objects.
Method 1
1. Go to File > Libraries and Objects > Import Rhino 3DM File as Object...
2. Select the 3DM file to import and click Open.
3. In the Information dialogue box, click OK.
4. The newly created object can now be found in the Embedded Library.
5. Place the object to verify how it looks.
Method 2
Exporting & Archiving Content
Once 3DM content has been imported and converted into a GDL object it can be exported to an office library for wider and repeat use. Visit the link below on exporting content from the Embedded Library. Exporting Content from the Embedded Library