We have an opening from the basement into a crawlspace, its maybe 3' x 5'. There was just some scrap chipboard leaning over it when we moved in. I took that scrap and cut it to the size of the opening and attached hinges and a latch and then framed it inside. Then used 1x2's and made one of those can rotators on the inside of the door so when you open the door a little bit of storage is there. Then build a second can rotator and hung is on rails just inside the opening so we have a second row of cans there without taking up much space.