Kettlebells in recent years have become more and more popular with men and women training in gyms and at home. They are affordable, transportable and deliver great results as can be used for a multitude of exercises.
I would say the Kettlebell is one of the easiest pieces of equipment to build a circuit of exercises with, along with adding in some body weight exercises you can literally train the whole body.
Here is an example circuit:
Russian swing (2 handed swing) (hamstrings, gluteus, core) 15-20reps
Single arm Row (mid back – rhomboids, front shoulder, core) 15 each side
Goblet squat (quads, core, gluteus/hamstrings) 15-20 reps
Single arm shoulder press (or both arms if you have 2 Kettlebells) (Mid shoulder, core) 10-15
Press ups (chest, shoulder, tricep) 10-15
Plank Holds (core, shoulders, upper back) up to 1 minute. Rest at the end of each circuit for 2 minutes and repeat for up to 4/5 rounds.
I have chosen very basic but effective exercises here which can be modified and adapted to make the workout harder or easier.