Our local Pound Land shop has a wide range of jewellery, earrings etc. with a range of patterns/ shapes / crosses etc. As they are made of thin metal they should be easy to cut & then glue to a base, then mix some sand with wood/PVA glue. Spread that over the jewellery (to fill gaps/half bury ruins) spot of dry=brushing & the jobs a good-un.
ALSO
The Works has a nice line of laser-cut shapes. One pack is full of various (Gothic looking) crosses, while other (possibly of use) packs include lattice frames, which when cut up look like broken iron work.
Hope this is of some use to you.