I wanted some light vehicles to use in various Alien Squad Leader armies, generally for alien forces, as I am pretty well-catered for when it comes to Human vehicles. I was really taken with these ones from The Ion Age. They are described as Sphera Attack Orbs for the Shia Khanate Legions, but I will be using them for my Alien Imperial army and also for my as-yet unused Alien Imperial Strikeforce. I am sure that I will find other uses for them, because they look pretty versatile to me.
I thought that green would be a fairly generic colour to paint them, seeing as it will fit in with most colour schemes. Before I glued them to their bases, I trimmed off some of the resin at the bottom of the vehicles, to give a larger area for the glue, but also to allow them to look as though they were slightly sunk into the surrounding terrain. I've also allowed some of the ballast to stick to the lower parts of the revolving tracks, hopefully looking like they are rolling along and kicking up some regolith or whatever the planetary surface consists of.
I think that these would also work in a Mechanoid army, maybe as Recon Droids. Anyway, they are nice-looking models. There are also larger versions of these circular vehicles with big guns and different variants of these small ones with different weapons options, so lots of ideas for a complete wheely army if that sounds like something you might want to create.