Randy, building a hatch is pretty simple. Take a piece of paper and draw out the hatch, full size. Position it where it should be on your plane. Mark that area with an outline so you know where to cut. After you cut the stringers and sheeting in that area you will need to build a frame around the perimeter to enclose the opening. The hatch too will need a frame and it is hinged at the top with a piano type of hinge. You will need either a small hatch release or you can buy rare earth magnets at Radio shack and use one to keep your hatch closed..Hope this helps BobH.