Oh yes, I know the perfect-ish plugin for making perfect circles like that.
I use this plugin a lot, called qCmdUtl. With that plugin you can use rotate pivot option to make nice circles
To use, first select the rotate pivot option, then select the Red Part (which would be placed in the middle of your circle area as seen below, can be anything really) , then you would select the model you want to move around your circle. Once selected press CTRL + D and then rotate, by whatever degrees.
