I have used press moulds for various bits and wondered if it would work for a tabard.
I made my mold from greenstuff and used a tabard from the Grey Knights Terminators sprue as the casting piece. Unfortunately my mold was not deep enough and the chain didn’t come out very well.
I used the cast piece anyway hoping that after it was painted it would be less problematic.
The actual tabard was cut down to fit the Marine sized figure and then smoothed out etc as best as possible.
I think the result came out better than I expected and I want to use this technique again as it can easily give you detail on your casting like the chain and cross on this tabard, if your sculpting is not that great like mine, but I will need to remember to make my new mold deeper!