Hello,
Sorry I never got back to anyone, but shortly after I posted my question, someone told me to just buy a high quality, leather money belt that has a zippered compartment on the inside lining of the belt. It runs the entire length of the belt, from buckle to sizing holes and then just fill the compartment with No. 9 birdshot. Then zipper it up and put some Loctite on the zipper, to make sure it stays in place and BOOM; I had my sap belt.
Works like a charm.
Went 'John Wick' on some dry wall to test it out and you wouldn't believe the damage.
Money Belt: https://www.amazon.com/Hidden-Money-Pocket-Travel-Leather/dp/B01M5F5F4F
Lead Birdshot: https://www.precisionreloading.com/cart.php#!l=SH&i=LMAG9
Thanks all!