The aluminum used for the bottom shelf of the TV stand is 1 x 0.375. For the shelf it is essentially a tongue & groove joint, I cut a groove into the wood and the aluminum is the “tongue”. For the legs, it is a mortise & tenon joint, I cut a mortise in the wood and the aluminum is the tenon. I shaped the aluminum in the “front” to be appropriate. I then pinned the joint with some 0.25 aluminum round stock.