I assume you are talking normal home networking and not commercial, in which the heat while there and needs to be vented, it's not a huge amount of heat.. Commercial racks have perforated doors front and back. Fans in the equipment pull the air from the front of the rack and exhaust out the rear. For home equipment it won't really matter. If you are talking commercial equipment foyer home then the rack is 19 inch rack. Wikipedia has a pretty nice article on the specs for 19 rack standard. Do not put your wireless router in a metal cabinet. You will shorten is range. Not sure. Would go,the expense of making one. There are plenty on the market. If you are going to put commercial equipment, be advised , because most of this stuff is in DataCenters it can be noisy. Way to noisy for a home environment.