I have a website for an art society set up. The categories in my portfolios are the mediums that artists work in, so that people can search for their preferred medium.
This works well on the page where everything is listed. It falls down inside an individual portfolio. The images display well on the left and the artists bio is on the right. At the bottom of the artists bio is a list of categories their work falls into. If you click on any one of these categories within the project, You end up on a 404 page instead of back in general portfolios, looking at all the artists who work in that medium.
In the case of printmaking, it takes you to a blog post about printmaking.