If a customer gets a certain weight of one specific category, we need them to be charged a flat rate. For instance if they buy 1000 pounds of White Stoneware and 1000 pounds of Loca Moca (both in category Moist Clays>Trinity, the total cart charge should be $600. So we want them to be able to buy any amount of clay from as long as it totals 2000 pounds. I set this up in Cart rules with attribute: brand-trinity ceramic. But it’s not working.
This may not be possible, tho only option here would be to use the fixed price, but it will show fixed price of the product for each item on cart under that category.