How to import: Layout Three column in to Builders?

Hello All,

I'm really new to Panels, I started learning Panels this week but I'm stuck with critical question: (or maybe more a feature?)

I see Panels has a set of default layout Columns 1, Columns 2 etc.

I now understand that I can create my own layout with Builders, but how come I can't import one of the current default layouts in Builder so can adjust it from there and don't need to re-create the whole structure (Columns) etc?

Perhaps this is already possible, but I didn't find the option yet?