DIY Rustic Mantle Shelf

After we had our freestanding fireplace installed, I installed a mantle on the wall behind it. I really wanted to be able to utilise it as a display mantle, despite the flue being in front. Below is the mantle surround and shelf I originally installed. The shelf was a rather thin piece of pine, stained a beautiful shade of walnut.
I had seen many "floating" style shelves, which I also wanted to attempt. For this this project, I purchased some more planks of pine and stained them the same walnut shade. Then I cut pieces to fit the front and sides. I left the original shelf there, and attached the new pieces with nails. 
The problem I faced was the brackets on the wall were longer than the base of the new shelf sides. I thought about leaving it open,  but there were so many angles I could see it and it just looked unfinished. 
So I got another piece of stained pine, measured it out to fit an cut out the gaps where the brackets sat. I pushed it up snug with the rest of the base of the mantle and nailed it in place.  It fit perfectly! Problem solved. 
 You can still see a small amount of brackets, but it's hardly noticeable.  I love the thickness of the new mantle.
It looks so much more prominent and provides a lot more contrast to the wall.
This project costs less than $20 and has a huge impact.  The wood add so much warmth to the room, almost as much as our fire. :)