I've been thinking about it a lot, and washi tapes as borders or background cutouts would be really nifty. Instead of having a white cutout with a hole in it, how about some fancy looking tapes? Could be a set of them that fill in the whole background one stripe at a time, maybe make them semi-opaque to give that real washi-tape feel. They could be thin or thick, have all kinds of designs, be nice for specific holidays. Also I totally need these for a pet's bullet journal TC.

Those are pretty! Support.
In loving memory of Need posting achievements?Then join Posting Frenzy Achievement Items - searchable list List of Borders and cutouts New at Fresh and Flavorful Ping Group
I like this idea as well. They could be at Thumble and Co., or a Quest Shop (either Cinthia or Alexander), or multiple places depending on the designs.
I would love to have washi tape avatar borders!
I think this would be charming!
And you know, they'd look great overtop some plain color, full rectangle backgrounds. Like, what about a background that was just solid black? It would really make the Light Pen items (currently I'm wearing them at the time of posting this) pop. Or solid lavendar or pink or blue for the washi tape? Or red or green or yellow to show off the pretty pattern cutters, like the wearable bookmarks?