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 Solar System Model
Solar System model - Wikipedia
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
solar system working model making for science project - diy at
Make A Solar System Diorama - Little Bins for Little Hands
How to Make a Model of the Solar System – Scout Life magazine
How to Make a DIY 3D Solar System Model
DIY Model of our Solar System - hands-on project for lower el students
7 Options for Creating Solar System Scaled Models - The Owl Teacher