About this 3D model

This is a set of idler wheels for use with the Lego Technic rubber tank tracks. My Mindstorms set only came with 4 wheels and I wanted to have more interesting track shapes like triangular or trapezoidal tracks, so I needed more wheels. I started modeling the standard wheel, but without the teeth, then I made one as small as I could while still having the clearance for the inner rubber guide row, then I made 2 larger wheels to accommodate different needs. I then tried to make the outer and inner cog teeth and I managed to create something that will work with the standard gears.