Spacecraft Blueprint
A spacecraft blueprint is a valid finalized spacecraft design made using the designer, that has been published to the spacecraft blueprint exchange, or burned to media, and is ready to be manufactured.
If the blueprint is published to the exchange, it can then be further published onto the Steam Workshop. This allows other players to easily download and use it.
Unlike buildings, a spacecraft blueprint must be saved onto media that is in the player's inventory in order to be selected at a spacecraft factory.
Details
A spacecraft blueprint displays stats about the ship. This includes things like the cargo capacity, HP, crew, weapons, etc.
In addition, a screenshot of the ship is shown. This is selected when finalizing in the designer, and is used for both the in-game blueprint exchanges, and the Steam Workshop images.