Materials needed :
a printer (inkjet or laser)
waterslide decal paper (paper types correspond to type of printer, also comes in clear and white)
It's kind implied that you'd need to use a computer to put the images together and resize them to fit your nails. I printed my finished collage on regular paper just to make sure the sizing was ok, and had to go back and tweak with them before the final result.
Once you print on the decal paper, let the ink dry before sealing it. I left mine out to dry for almost an hour just to be safe. Then spray it with the clear coat (I had a can of Krylon Crystal Clear that I used for other projects) and do 2 to 3 coats and let it dry. I left mine to dry for nearly 24 hrs just because I didn't need to use the decals ASAP but I believe the clear coat dries sooner than than.
It's important to seal in the ink. otherwise once you place the image into water it will just run. I've read that some people use clear coat of polish, just like making traditional nail polish decals, and it works too. I haven't tried this method yet as it's much faster to spray the whole sheet all at once.
Application is just like a regular waterslide decal - cut out the image and put it in water for 30-60 secs, then it just slides off the paper backing and can be placed onto the nail. It doesn't have any stickiness so it either needs to be secured with a little bit of clear polish or if it's smallish, then just covering it in topcoat should keep it in place.
To be honest, I was really nervous making these and kept thinking I'll mess something up and it will be a flop and a waste of paper. So I spent a lot of time looking for images to make sure I'm using up the most of the space on the page and towards the end I just wanted to be done with it so I started adding non GoT related images. But I did my first mani with one of these decals and it felt go great to finally see the mani that I kept envisioning!
I hope this was helpful!