Is it possible to add a new fastener category in toolbox?
For example, under Bolts and Screws I want to add a new fastener category call "Eye Bolt" and inside the category there are different types and sizes.
This video might help you out: Adding Custom Hardware to Toolbox
While it is possible to go under the hood and add a new fastener category (unsupported by SW), looking in the SW2016 toolbox, I do not see eye bolts listed anywhere (but I do not use tool box so I could have easily missed them). If you are using SW2017 and eye bolts are in tool box then you should be able to add the category. Hopefully you know your way around sqlite databases...
This video is pretty good to Configuring the SolidWorks Toolbox - YouTube
Retrieving data ...