cost effective because we'll be using T-72 Chasses on the Karrar!!!
But overall both Zolfaghar & Karrar projects are programs that lack foresight for Iran's future armored battalion.
What Iran truly needs to do is to build and invest in a bunch of oven presses (Maybe heat up and press sheets of alloy into one peace) and design a multi section Chasse that can be easily interchanged where the designs and materials used for the top and side section of the chasse can easily be modified to be used for cheaper and lighter IFV/APC or heavier SP Artillery or whatever you may need which will allow you to mass produce the bottom sections, wheels, one or two types of engines,.... And any additional expense will make up for it in the long run once mass produced and you can mass produce a large portion of the spare parts needed for the chassis for a large portion of your heavy equipment in your armored battalion and ease battlefield maintenance with interchangeable parts and it also allows Iran to produce larger numbers in a shorter amount of time based on demand using less facilities which allows you to build better protected sites and better defend those sites.