Household Items
Make a "cell in a bag" with common household materials. Using a Ziploc bag as a cell membrane, fill it with different materials to represent the different organelles. Ideas include jelly or uncooked kidney beans as mitochondria, noodles for Golgi bodies, sand for ribosomes, drops of oil for vacuoles and a hard boiled egg cut in half for the nucleus and nucleolus. Once all the organelles are in place, fill the bag with a thick clear liquid such as corn syrup or detergent to serve as cytoplasm then seal it. Write up a note card explaining the cell and why you chose the objects you did for organelles.
Representative
Instead of modeling organelles based on shape, a representative model of a cell models organelles based on function. With this model, the cell membrane could be a plastic bag or cardboard box with small holes cut into it. Inside the "cell membrane" you can make a diorama of organelles: a battery could be the mitochondria, sandwich bags filled with water can be vacuoles, protein bars can stand for ribosomes and a model of a brain or a smart phone can be the nucleus. Under each item, write what organelle it represents and why you chose it.
Single Material
If you excel at working in a certain medium, such as clay, paper mache, dough, Legos or wood, consider making a cell model out of this material and coloring or dying it as you see fit. Aside from providing a chance to show off your artistry, this option allows you to make more accurate, detailed models of organelles. Write a paper explaining what the organelles are, how you made them and the steps that went into making your model.
Structure
If you are modeling plant cells, consider constructing a model of a leaf or branch out of little rectangular boxes of cells. The cell wall of plant cells makes them stack on each other in a lattice-like structure. Use wooden splints, plastic or wooden toothpicks or another similar material to build the shape of a leaf out of little boxes. Inside each box, place a pom-pom and a small piece of pencil lead or cloth, depending on the size of the cells, to serve as the nucleus, then cover the whole thing with green plastic wrap. This project emphasizes how every living thing is a structure of cells.