These are so easy and cute. Just make a small snip on the corners and where the tape would otherwise make a bump over the metal part. Washi tape: on hand. Wooden clothes pegs: on Obi's 1 Euro rack (PS- Obi also has those mini rolling adhesive thingies like this for 1 Euro). Easy.
These have been great on my DIY fabric pinboard. I've also seen them used on gifts - shoot, give them as gifts! Where would you use them?