Depends what you want to make it out of.
You can make it out of:
Plasticine
Paper mache
boxes
Paddle pop sticks
paper
cardboard
etc
The best idea would be making a wire frame and making it out of paper mache
or by using plasticine
What materials do you need to make a 3D model of an animal cell?
You can make a 3D model of an animal cell out of almost anything.
The main things to remember are that you will need several colors of material, to represent the main parts of the cell. Popular options include plasticine (which obviously comes in several different colors).
Alternatively, you could pain the different parts their distinct colors, so long as you use a material that paint will dry on easily.
You also need to consider the structure of an animal cell... Although it's not perfectly spherical, a round call of some sort would be the ideal representation of an animal cell.
In the video below, the example shows a styrofoam ball being carved into, in order to display the "internal workings" of the animal cell.