Apple - Where does Apple Configurator store ipsw downloads?

Since Apple Configurator 2.0 they are downloaded in:

~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Downloads/ACUDownloadFileOperation/

and stored in:

~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Firmware

I've figured out how to point Apple Configurator at the IPSW that iTunes has downloaded as follows:

Then use the dialog with Other... to add each and every IPSW that you've already downloaded. Since ~Library is normally hidden, you may need the go to shortcut to type command-shift-G and then ~/Library/iTunes to get to the filesystem location where iTunes has downloaded current IPSW files.

By adding multiple iOS versions, you can point the configurator at already downloaded IPSW and avoid the wait / duplication of Configurator re-downloading the same file and storing it away in some obfuscated database file at ~/Library/Containers/com.apple.configurator/Data/Library/Application Support/com.apple.configurator/Resources

I haven't found a way to remove IPSW from Apple Configurator, but knowing I can keep them where iTunes prefers is workable for my case when I'd rather not wait for a long download and/or a duplicate set of IPSW on a particular Mac.

I am using version 1.3.1 (274) of Apple configurator, the following worked for me:

Apple Configurator: Managing iOS device software had the correct location for the IPSW files in my situation.

~/Library/Containers/com.apple.configurator/Data/Library/Caches/com.apple.configurator/Firmware/

I had to create the Firmware folder as it didn't exist yet but it I was able to successfully copy the required IPSW file to this location and deploy it to an iPhone without AC going to the internet to download it again.