Actually--I think there's a way to do this, but it's a little bit complicated. I learned this really recently, actually, from
this person's page, but I'll try to explain it in more detail
(Please use this method responsibly though, don't go around taking other people's QR codes for the heck of it and claiming them as your own. It registers the pattern as yours rather than someone else's, so I'm assuming it'll work for putting them up at Ables'. I'm really stressing that you don't use this to claim someone else's QR patterns as your own, people put a lot of work into making patterns for ACNL and like I said, it registers the pattern as if they were yours, with your town name/player name, so please be cautious putting them up at Able Sisters and having your friends over.)
Using
this site, upload a QR code made by you (with "Load ACNL file or QR image"). It doesn't have to be anything fancy, you're just looking for the area that says "Title, Creator, Town." Under there is a button that says "copy creator," click that. Then, open up the QR image you want to load up into the game. Click "paste creator" and then the big QR image underneath should change. You can scan that directly into your game. You know it will have worked when you can modify the design.
I haven't tested to see if you can copy/paste the original creator's name into the text fields and have the game still register it as your own pattern (or if it's based on the relationship between the name and the second ID), but if that works, then definitely do that. Just keep in mind that it should show up in your dream town patterns if you have those enabled, too. I can't really stop anyone but please please please only use this for decorational purposes and not "hahahah look what i made everyone" purposes
Another thing I can't really control but it's good if you have the original designer's permission to do this, like on the page mentioned at the beginning of the post. Generally if they're made for signboards then you have the right to go ahead and do it, but clothing might be a little trickier since people can copy them to their design inventory with your name plastered on them.
Anyways oops I just woke up so there might be some weird grammar issues in this post but I hope it's understandable enough
