Get Test EXT2 IMG file

I have a task for university to deal with EXT2 file recovery. The problem is that the example drives (as IMG files) we got only contain one block group. I want to test if I read the drive correctly so I need more than one block group. I tried to create an IMG file from my Kubuntu USB drive but did not manage to do it. I searched online but found not a single IMG file to download. Google only wanted to sell some ext2 drivers to me. Where can I get an ext2 IMG file from?