Maybe this feature already exists and I just don't know how to access it...
First - note that in my opinion a golden opportunity exists for Zenfolio right now. Another large and well known site that allows photographers/designers to upload custom designs and create products is messing up big time right now (dramatically so, in fact). A lot of people are looking for alternatives.
But on that site I can (for example) produce a search result for clients that shows all photos/designs for a given product (eg., a journal or a mug). I can also create a custom crop/sizing for each product.
I realize that Zenfolio began (I think at least) as a photographer's site. But since you are now offering a large array of products, you should make it easier to present those products to a prospect.
As it stands, it takes too many clicks to get to a product (assuming you know that you have to add a photo to a cart before you can see what products are available - and even then you need a certain level of expertise to be able to crop correctly to end up with a nice product).
I would love to see such a capability added (along with API calls to support tapping into it). I think this could be a major coup for Zenfolio, especially given all the other good things you have going for you.
I can elaborate on this at length but want to avoid too long a post if there is little interest. Hopefully I've said enough to get an initial point across...?
Thanks,
-ldl-