Background: Creating a dynamic shortcode based on user inputs. This shortcode should change the output of `do_shortcode` based on the fields the user selects.

Example: On a page, a user selects 

> "Show me:  (X) Skateboarding (X) Basketball ( ) Hockey"

When they click submit, the shortcode to do this should show as:

    [shortcode_name types="Skateboarding, Basketball"]

and since Hockey wasn't selected, Hockey wouldn't be included.

That's what I'm trying to accomplish, I'm just having a hard time locking down how to actually do it.