You may ignore this post unless you are my sister or my niece. Or I suppose if you are really curious how to make a combine cake, you could read this. It's heavy on the pictures, because my niece is planning to make one for her 4-H project and this was the easiest way to share my pictures. At times like these, I'm thankful that my husband is a photographer.
So I started with a quarter sheet cake. (I suppose you'll start with a 16"x20"x2" styrofoam block. I cut a piece of wood about 5x8 inches. Maybe not quite that big? I covered it with foil. Then I cut 2 slabs of cake that size as well, and piled them on top, with icing in between. Here is a picture of that:
Then I picked an end to be the back, and rounded the edges, like this:
I cut a wedge shaped piece of cake to be the cab, and attached it with icing and shish-kabob skewers. I also made a hopper like a rectangle with a bowl hollowed out inside. Here are some pictures of those:
Then I covered the whole thing in green stars, like so:
Here is a close-up of the cab, after I iced the top, but before I did the windows. Notice how the hopper is right up to the cab on top:
I poked in a bendy straw to be the auger. I cut the bent part a little shorter. I used a smooth tip to pipe icing on all around it:
I dipped my finger in corn starch to pat the icing smooth. The corn starch just soaks in:
I put on the toy combine head. (I'll get it to you somehow!) I attached a ding dong with frosting for the front wheels, and chocolate covered donettes for the back wheels, and a little yellow icing for details. Candy corn in the hopper:
Gray for the windows, lined in black:
Good luck! I know you can do it.