Albums allow you to see the aggregate figures from across several projects. So they are useful for reporting or high level analysis. In the Albums section, add a column for each album you'd like to add then mark with a Yes the projects you'd like to assign to each album. A project can be part of multiple albums.
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On Makerble we don’t have Album Categories as an actual entity, however we include them in the Blueprints as a way for you to think through the different sets of Albums you want to have.