Thanks for clearing this up 
It actually sounds fun to make my own cases now, rather than buy them. I had no idea they were getting the prints from this website.
Do you know where I can get cases that fit NES games?
Yeah many sites steal the copvers we make.
We don't sell the covers we make but make them freely available to everybody *(including the assholes

).
Making covers is fun, but making high quality ones is tedious.
UGCs fit NES, as do bitboxes, Seymor onion cases (if they are ever done

) and Shadowfox is maybe (or probaly if not definitely) making cases for NES aswell.
All cases except bitboxes use same covers, bit boxes have their own slowly growing collevtion of covers.
We do covers per request as well.
To get your request fulfilled more likely, provide high quality 300DPI (or better yet 600DPI scans.