Here is a red oak shelf, designed to match an existing shelf from the 1970s, which Spouse owned before I met her. This shelf is a scaled down version of the original, made by request from Spouse.
Decades ago, red oak was the cheapest hardwood available. It was all that us poor students could afford. We would pool our funds, order a huge truckload of boards, get it dumped on the driveway, and divide the boards among us. I don't remember how many truckloads we bought during those years. I was so burned out on red oak. This shelf came from the first red oak board I have bought in many decades. I enjoyed it, mostly. The shelf had some interesting twists and curls in the grain, not shown.
The corbels were rough cut using a bandsaw, then trimmed to shape with a top/bottom bearing router bit. I made a pattern from 1/4 inch MDF. I forget which bearing I used. I used a 1/8 inch roundover bit on the corbels, like the original shelf. The edging on the shelf and bottom board is "classic Roman ogee", a close match to the original shelf.
I glued only the back of the shelf to the bottom board and the back of the corbels. Unlike the original, the rest of the shelf is not glued to the front of the corbels. It was my idea to allow for wood movement. I have not seen that done before, so we shall see if it works.