Sorry, I don't have a pre-made script to do this job. All of Kibana's saved dashboards, visualizations, searches and index patterns are stored in the .kibana index in elasticsearch by default. You could grab one of the official Elasticsearch Clients for your favorite scripting language and write up a little script that grabs each dashboard and it's related objects (vis, index pattern, and any saved searches). Since ES exposes a REST API you could even do this with a simple shell script and cURL if that's your preference.