Rigging controls

#1

Hi guys, i saw on the many tutorials on biped something like the empty square or rectangle controls, how can i reach this controls on biped? I also on many artists projects see in the cat rigg circle controls, i know how asign this controls on bones rigg, but technic like the bone > control > bone linking doesn work on the cat rigg
Do you have any experience how to create some controls in this both (biped,cat) ? I will glad for any advice thank u

#2

You could change the shape of the CAT to boxes.