Membership Cards

Some artworks for the membership cards. I still want to keep them slightly mysterious so if someone finds your wallet they wouldn't automatically know what this card was for. These could look good printed on matte stock with a gold Pantone or foiled. Again the black varnish or embossing could look really stylish too. I need to test these properly to select the best result. I want these to have crisp square edges as I think it is more appropriate than rounded edges.

Fronts:

 

Backs:

 

Or the back could be kept blank...