you can't make a silk purse (out) of a sow's ear
You cannot fashion something beautiful or valuable out of poor materials. What do you want me to do with this tacky fabric? You can't make a silk purse out of a sow's ear!
You cannot make a silk purse out of a sow's ear.
Prov. You cannot make someone more refined than he or she is by nature. I've given up trying to get my cousin to appreciate classical music. You can't make a silk purse out of a sow's ear.