AutoCAD Inventor :: Storing And Retrieving Features From A Library

I need to create and maintain a library of hole features of varying shapes and sizes (there will only be around 10 variations).  The goal is to be able to programmatically retrieve a feature and then place it in the current part.  Ideally I would like to be able to assign each an ID to each feature that I can use to programmatically retrieve it. 

My first thought on how to achieve this is to have one master part file that contains all of the features.  When I need one I can open that file and somehow copy the appropriate feature and then place it in the target file. 

Or maybe it would be better to save each feature in its own part file? I'm not so much looking for code as much as general guidance on whether either of these approaches sound reasonable.  Maybe there is a better way to programmatically store and retrieve features from a library?