I wanted to go that way myself and my lfs owner told me all his racks are built on 2x4 construction; hes got alot of weight on that. i WENT WITH 4X4 IN CORNERS (*caps lock) 2x2 length into notched 4x4 and 2x4 front to back. Tomorrow I will wrap it in 3/4 ply and cut out the doors. Im not sure if i want to go with a 2x4 vertical leg in the middle being its only 48" long but i have the wood and probably will just for hots and giggles. Thanks for the reply; Ill send some pics
when im done