If you don't have a pile of scrap wood, purchase a piece of 1-inch or 2-inch by 8-inch lumber, some wavy wood trim that's 1 ...

At the front of his house, built in 1930, he has three of these decorative brackets. Upon these he attached a top piece of wood to act as a shelf for placing condiments when he barbecues.

Make the screws a decorative element. I've used "countersink washers" for this before. 3. For future use, attach the back to the wall first with screws where the shelf brackets will go.