How Do I Build A Model Of Mars?

First of all take a round balloon and inflate it. Take PVC or PVA glue and cut pieces of newspaper. Take a brush and apply the glue on the balloon. Paste the pieces of paper to the balloon. Repeat it to form many layers. Allow it to dry. There burst the balool to get a hollow ball of newspaper. Paint it according to your need.

You can take nine plastic balls:  step1: Take 1 big ball and then according to the size of other planets.  step2:now make a mixture of water to fevicol as 2:1  step3:now put a layer of fevicol on the balls and put some layers tissue paper(2to3 layers)   step 4 ; now colour the planets neatly according to their colours in the atlas etc  step 5 :now take a big card board box,keep ti horizontial & cut its on of the side.colour the inside with dark blue colour & hang the planets inside it with a cotton thread

Get a round balloon and blow it up to the desired size. Tie off the opening and stuff it into the balloon. Cover it with layers of papier-mache and let it dry. Use plain newsprint, not newspapers. Draw the main features on it, and add some more papier-mache for mountains. Use watercolor paints with minimal water (so it's thick) to color things like the polar icecaps, orange & red features.
 

I Guess you could make a model out of clay,and make the creators and holes with a butter knife.

Could you buy a sphere from the craft store and paint it and then splatter paint on it for the crater? I am doing a science project and I think that is what I am going to do. I don't know if that would work but I will try to post something if it does.

Well I was thinking take a hamster ball and wrap it in cloth of some sort.. Then paint it the color of your need. That is what I did for my science project and I got an A:)