Since the entire definition of a Look (model, explore, fields, pivots, filters, visualization settings) is available in a Looks "share URL," you can quickly and easily move individual looks across models or explores in a Looker instance, or even across Looker instances, by copying the Share URL, modifying the project/model, and pasting it back into a browser window. Here's how to do it:
1) Explore a Look from the gear icon in spaces, or using the "Explore from here" link on the Look page
2) On the explore page, navigate to "Share" on the gear menu
3) The "Expanded URL" contains the complete definition of the Look. You can update the instance, model, or explore in the URL to open up that same look in another environment:
https://[INSTANCE URL]/explore/[MODEL NAME]/[EXPLORE NAME]?....