I made this Homemade Construction Site Birthday Cake for my son Carter's 3rd birthday. First, I made two large rectangle cakes. I took one of them and arranged it on a foil covered cake board. I then cut the other one into three long sections (measure them first!), saving a bit of extra cake to create the ramp into the construction "pit". I then set one section lengthwise next to the base cake and the other two on top of the base at right angles. I then cut the left over cake into a ramp shape and set it at an angle from the inside corner of the pit so vehicles could "drive" down it.
To cover the cake, I used butter cream frosting of various colors (I just made white and then dyed bowls in the colors I needed). I put yellow frosting around all the outside, tan in the construction pit and along part of one top edge (for the dirt), and then a strip of black for a road next to a strip of gray "sidewalk" along the other top edge. I used white Good N' Plenty candies for the dashes in the road and then put silvery sprinkles on the white ramp to look like gravel. Then I just added a bunch of purchased plastic construction equipment toys on the cake, driving up the ramp, working in the pit and along the top. The dump truck is unloading chocolate covered peanuts, the toy going up the ramp is carrying a pretzel rod and the trucks in the pit are unloading the crushed up inside of a Butterfinger. The partially built wall inside the pit is made of pez candies.
Finally, on the outside edge of the cake, I piled up marshmallows, mounded icing over it and then graham cracker crumbs for dirt and had a vehicle drive up over the pile an onto the side of the cake.