The Idea Window
The Thumbnails Tab
Use the Thumbnails tab to keep thumbnail projects linked to the Idea they support.
The Thumbnails tab shows thumbnail projects linked to the Idea. A linked thumbnail project stays connected to the video concept it is meant to support.

Use New Project to start a thumbnail project from this Idea, or Link Existing to connect a project that was created elsewhere.
Linked thumbnails are also what power the YouTube Mockup generator. Use Preview Mockup to open it, then Bluprint uses the thumbnail project's derived cover image when it previews the Idea on YouTube-style layouts.