Create a droplet to output just the front cube face

Is
it possible to either edit ‘Convert SPHERE CUBE’ droplet, or create
something similar from scratch? I’d like a KRPano droplet that only
creates the front cube face from an equirectangular in order to use then
as thumbnail images. If the filename can be prefixed as follows
‘TN-panorama-name’ that would be great. If there is an easy way to
change the size of the cube face, then even better.
I have zero idea about how to create such a droplet so any help will be appreciated.