One-Price shipping for unlimited items in the same Store Cagegory

Summary: The discussion revolves around the concept of offering one-price shipping for unlimited items within the same store category. uneedmorecards initiates the conversation but does not provide further content. bonanza125 engages with the initial post, and uneedmorecards responds to them. Another participant, mcdougle4248, adds a response, though none of the posts include explicit content to expand upon.

Can anyone tell me how I can set up a shipping rule for a sub-category so there is one shipping price for as many items ordered in that category?

For example, under the category "Vintage Postcards" I want it to charge $.75 shipping for 1 item, or if they order 10 from that exact category, still just the $.75. But only items from this single category.

So basically like a shipping promotion for one category only? I'm thinking this can be done, but I haven't figured it out yet.