Heya everyone! Since I appear to be chronically unable to reliably add the ".L' to every bone that will be symmetrized I decided to (dundunDUN) create a script!
This script checks all selected bones for the ".L" suffix. If the bone does not have the suffix it will be added. As usual, the active object must be an armature. Be careful to not select any bones you don't want symmetrized.
This is my very first Blender script and it is very simple. I tested it and it appears to work okay but if you have any issues please let me know.
https://drive.google.com/file/d/1EeYnCxQuGN-X_WPOE_CwGv6zqMyMdFfd/view?usp=drive_link
Not sure if you know this or not, but blender has a naming feature. I use it all the time, because I'm Lazy. So I just name normal(Thigh, shin, upperarm, forearm, hand, foot, etc) then select the bones right click->Names->Auto name Left/Right. Then I right click->Symmetrize.
Note: I sent request to acces your script.
OMG I did not know this! Holy moley this will be so useful. Thank you!