best way to replicate a favourite shape when editing a simulation?

I am working on a large eLearning project which holds multiple screen recorded simulations.  I am adding an empty box around the target area on each slide and although they are not the same size each time, they follow a consistent format so that the user can readily identify them.  It's getting quite tedious to create them for each slide, does Storyline offer the option to add a favourite shape to a toolbar ? Or has anyone come across an efficient way to do this?  Thanks!