Connecting user created content to an ordered Product

[Paul Hummer]

I'm trying sort out how to connect user created content (different types of models) to a specific ordered Product itself (an instance of the Product, as it's ordered, not the Product definition). For instance, let's say that a user can take a drawing they have made on a site, and buy a print of it. I might make a "Drawing Print" product, but it doesn't seem wise to create a Product every time a user creates a drawing. I looked at Attributes, but obviously those are just as static as just modifying Product. I considered making it an Option, but it doesn't appear that Options have even the strictness/richness that might come from Attributes. I *think* I want to use something similar to Entity for Option, because the content could be a drawing or a photo or whatever, and the "Print" Product would just need to be linked to that record when the order hits fulfillment.

What's the common way to connect this type of user created content "metadata" to an Order?