One of my best makeshift things is my improvised cooling rack. Often used in baking, the use a cooling rack can be essential to make sure whatever you make cools evenly, quickly and keeps the integrity of the baked good. I'm surprised I have room for more 3 cookie sheets, there's definitely no room for a cooling rack.
What I do to is put two bowls out and balance that wire shelf I have in my microwave on top. Voilà...a very clever (if I do say myself-and I do) cooling rack.
Long and short of this tip: If you don't have that certain something needed to make your food, find something you can fashion yourself.