Kibana 3 - Custom Panels

We currently use Kibana 3 and would like to explore the possibilities to write customized panels to cater our usecase (say like histogram using values or stacked bar chart).

Are there any documents/guides available targetting this topic?

Thanks
Arul

Nope, KB3 is deprecated now too so there's unlikely to be any.

There are no docs from Elastic, but there are many community resources if you Google. Also, in Kibana 3, the process is quite simple -- go to [kibana_dir]/app/panels, copy one of the folders representing one of the built-in panels, and use it as a template.

As Mark mentioned, from the support perspective Kibana 3 is now deprecated and you may want to consider basing your deployment on Kibana 4. Kibana 4 extensibility goes way beyond custom panels, as it has a true plugin interface.