Weight reduction for dinos of some items


I’m wanting to change the weight of stone for a doedicurus and metal for an ankylo, however I can’t seem to find anything within the BPs to set this. It’ll work like how the Beaver adds weight reduction to items, however I believe that is due to the smithy being on the beaver right? If so, would I need to add a smithy to the doedicurus and ankylo and if so, how would I do that?