Smaller design meant for business cards, larger for pictures and postcards as shown in the video below. More info on inspiration etc to-be-published on Techadjacent.io in the near future.

3D-printed studs are the same for all designs. The frame/acrylic face is cut out on a laser. Design files are included, so perhaps it could be modified into a fully 3D-printed hexagonal frame setup.

M3 screws and nuts are used for attachment, and well as (optional) CNA glue

This M3 kit (Amazon affiliate) should cover you.