Select Panel Node Layout on Node edit form
It sounds like you are using Panels (presumption based on the column names), so this is very easy to achieve. 

In Page Manager, enable and edit node_view. Create a new panel variant. Enable Selection Rules for the variant. Add the selection rules "node_type = product" and "field_layout = 2 column". 

Then carry on through the rest of the config, ie choose 2 column layout and put in your fields/blocks/etc. You will then have to create 2 more variants (or clone and edit the current variant), changing the selections rules and layout to suit.