Use a sponge to soak up concrete mix in whatever shape you desire and let it harden into a hardened version of what you just cut out! Pavers or garden accents? (I would wear rubber gloves while dipping/soaking!) Worth a try.
Made from cereal box or other cardboard. Could cover with scrapbook paper before scoring. Could add a little dimensional paint for raised metal affect and then paint and dry brush so the design shows well.