Using cardboard sheeting (or even box!), a utility knife, a straight-edge and some tape create the sub structure for the stadium. Cut out a base shape onto which everything will sit. Build each element as a separate piece. Eg, build 2 rows of lower seating, 2 rows of upper seating, 2 rows of curved lower seating, 2 rows of upper curved seating.
Using wide packing tape, reinforce corners to keep boxes in newly formed shape (i.e. Seating rows). Using wide packing tape, adhere rows together, then attach to base.
Build the playing field a few inches high, so a box will fit beneath it as the end zones...which will house food. Cover in astro turf making sure there are cutouts for the end zone. Spray mount astro turf to box.
Cover entire stadium in foil, so the stadium can be used again! Make barricades to separate foods with rolled up foil.
Fill stadium with sandwiches, chips, guacamole, chicken wings, dips, veggies, pretzels, popcorn, etc.
Name your stadium!