The panel for this niche was ordered online, and a carpenter framed and installed the door so it's flush with the wall. The client wanted the cabinet to be virtually unnoticeable, so the panel was painted to match the wall. The inside of the cabinet is painted black, so the cords can't be seen through the panel.
This space already had framed sides with enough room to create a recessed niche. If this isn't the case in your home, Miner says you can build out more wall space to accommodate a niche. Make sure to frame the space so it's a little bigger than your electronic equipment. Add a shelf, cut a hole so that the wires can feed through to the TV, hang drywall, and you're all set!