I can admit that one of my least favourite decor items at most weddings (although not ones that I plan!) is the vessel used to collect envelopes, usually on or near the guest book table. I'm just not a fan of white satin mailboxes, birdcages, or anything with tulle hot-glued onto it.
I prefer to use out of the ordinary containers like tins, baskets, or unique vases, hopefully something unique that doesn't scream I hope there's some cash in that envelope and matches the theme of the wedding.
Here are a few items that could be re-purposed into a card box:
A Vintage Bread Box, from Grace Art and Antiques:
Antique cake box from Steptoes Vintage Wares:
Queens of Vintage:
Lunch Kit from Feather Your Nest:
Retro Vase from Steptoes Vintage Wares: