#To add external libraries for Eagle CAD
First create a directory under the /Users/[USERNAME]/ directory named
/external_lbrs
where [USERNAME] is the login name
In Control Panel goto options-->Directories goto the Libraries option and add the following:
$HOME/external_lbrs
note the directories are separated by a colon it should read like this
$EAGLEDIR/lbr:$HOME/external_lbrs
or browse to the external_lbrs directory it will display like this:
$EAGLEDIR/lbr:/Users/[USERNAME]/external_lbrs
where [USERNAME] is replaced with the login name. Copy custom or third party libraries to external_lbrs
The advantage of using this method is that when Eagle CAD is updated the custom or third party libraries will not be overwritten or lost.
For those searching for CAD libraries i recommend using this search site
This can provide CAD libraries for a number of CAD programs such as Altium, Eagle, EasyEDA, KiCad and more. If the part does not exist you can request for it to built. Try to make sure you have the technical documents that is required such as mechanical, specs, datasheets etc.
For example a part in a post on https://electronics.stackexchange.com/ here is the link: