The brackets are 20" (they have different lengths)
208 Series Ultimate L-Bracket by Knape and Vogt. They're about $20 for a pair and hold up to 1,200lbs. You'll use wall anchors of course.
For the shelf, I used a piece of black tempered glass, which you can order from multiple places online, or a local glass supplier. I got mine at
fabglassandmiorr.com.
I used 6 pieces of
Aleene's Instant Tacky Craft Putty to keep the shelf from sliding. There's no need to screw the glass to the brackets. The putty, weight of the glass, and weight of the tumbler keeps everything 100% solidly in place, and it'll be easy to move in the future. I have the same setup for my Batpod/Catwoman.