/cgl/ - Cosplay & EGL

Wondering if you gulls could help me. I'm making pic related by handstitching into a cotton-based velveteen. I've seen lots of embroidered stuff with the cabochons under the fabric but I'd like to put my fabric under the cabochons.

My problem is how to fix them together, I only found a couple of tutorials and they varied from ropey looking selotape methods to gluing with mod podge and glaze in the same way as stickers and paper. Does anyone have any suggestions? I don't want to muck up the fabric.