We are finishing a heavily rewritten shop in Zen Cart 1.3.8a.
One thing we just started was to create a Record Artist Filter that works in the same way as manufacturers_id does in the address bar. Namely to filter and only display products relating to a manufacturer id but using the record artist table instead.
In short, when the system loads a page with a url like
[url removed, login to view];artists_id=10, it should reload the index page and display products relating to that artist id only.
If no products exist, the default no products message should be shown.
If you need to see the filter working on the manufacturer_id, you probably don't know enough about zen cart to get this done within our budget.