I saw this tutorial for doing a Gudetama 3D nail and I had to try it:
The hardest part about doing this nail is making the face, which I had to do about three times before I got it right. It's time consuming, so I couldn't imagine myself doing more than one of these per hand. Maybe I'll try this again when I get some Gudetama nail decals (which I saw on Etsy). I did this on a fake nail, and just laid id on my thumb nail to take a pic. If I did this again, I would make it more 3D for sure.