Automation or app to back-up custom icons system-wide? No Time Machine

I am looking for an app or automation that allows me to back-up the custom icons and re-apply them after a clean installation.

I would love to be able to back-up the custom icons that i’ve applied all over my mac. Is there a way to do that? I use Dropbox to backup the biggest chunk of my data. So using time-machine wouldn’t work, because after a clean install, Dropbox does not want to reconnect to an existing iteration of the files. Dropbox requires you to re-download all the files, loosing all the custom icons.