You can make a solar system model out of many types of materials. The one thing you should keep in mind is scale as the planets are all different in size.
DIY Scale Model of the Solar System - ASTRO 3D
Out-of-this-world kid's craft: How to make a Solar System model Solar system projects for kids, Solar system for kids, Solar system model project
Make a model solar system to learn about the planets
DIY Solar System Models
Home Science Tools - Make a Solar System Model Make your own model of the solar system! It will help you learn the order that the planets orbit around the sun.
22 Piece 3D Solar System Model Kit for Crafts, Outer Space Science Projects, White Polystyrene Foam Balls for Painting and Coloring, Spheres and Dowels Included : Toys & Games
How to Make a Model of the Solar System – Scout Life magazine
How to Make a Solar System Model (with Pictures) - wikiHow
How to make your own Solar System (the easy way) - Fun Learning