Scroll down: http://hammersandhighheels.blogspot.com/2011/11/bachmans-2011-holiday-idea-house.html
Towards bottom of page: https://gardenviewcottage.tumblr.com/page/15
Paint center in black chalk board paint for memo boards.
You could decoupage them, either paint first or use as is. These trays I painted first before applying separately cut images. If you had several trays that are different sizes you could fasten them together by using candlesticks glued on.
I have seen a beautiful gallery wall of tons of silver trays hung together!