Share fields between commerce variation types? I have 12 types of products that have 4 similar property fields, for example: weight, force, collar size, noise level. There are many other different fields for each of the 6 types.

Is there a way to set up Drupal Commerce variation types so 'weight' for example is the same fieldname on all these products types?

I'd like to do this so that a faceted search can allow customers to search for weights or collar sizes, etc, across all product types.

Or any other ideas on how to structure this?
(using Drupal 7 and Drupal Kickstart 2)
Assuming you are asking about Drupal 7, the answer is yes. You can share base field types across product bundles. Each bundle will have it's own instance of the field, but the data will be stored in the same underlying storage system.

You can add them by choosing from the list of fields under "Add existing field" on the field editing screen: