SANDMAN0198

Good morning, I am attempting to build a 1/72 copy of the LUT for Apollo rocket in plastic, I am using the Edu-craft paper model as an example. My question is that when building the blast area that goes under the Saturn V engines on the Mobile Launch Pad, the paper model gives the impression of being slanted and or even rectangle in shape as to form a funnel. (maybe I folded or glued the paper wrong) But all the pictures I see show this area as a straight squared shape, with no slant only 90 degree walls all around. Does anyone has a picture of the area in question for better understanding?