From Tina:

Making your own decals doesn't have to involve buying special papers to do it. If you have Mod Podge in the house or Decoupage you can do it!

Find an image you like and paint mod podge(glossy) or Decoupage (J's complete coat will work too, but it doesn't dry clear enough for me) in three or 4 coats on the top of the picture, Letting dry between coats. When you have about 4 good coats on there let it dry overnight.

Then soak in warm water for a few minutes(the top will turn a light milky color), and rub and edge on the back side until the paper starts to lift off.(Or you can use your fingernail to peel an edge away) Peel off as much of the paper as you can. I find that placing the picture on a sheet of wax paper, face down, and then rubbing my fingers on the back will get a lot of the paper to "roll" off.

Let it dry and if needed repeat the process until all of the paper is gone. LEt dry again, and now you have a decal! Just place it where you need it and apply Mod Podge or Decoupage or whatever medium you choose to affix it to the egg surface.

Also, Photo quality paper works really well with this if you soak it long enough it comes off very easy!

From Stephanie Ramey: www.eggcrazy.com

I use a product called Omi-gel by Houston Arts that works very well. Follow the procedure as listed above.

Another way to make your own decals is to use waterslide decal paper. It is a special paper that you buy to run through your printer. Make sure you buy the paper for your kind of printer. IE...injet waterslide decal paper for an injet printer, etc...

These are a home made version of the decals you get from a ceramic supplier. You print your image onto a special paper, spray it with a special Decal spray and leave to dry. When it is dry you soak the prepared decal in water for about 10 seconds, slip the paper backing off and apply the decal to your egg.

Sources for the decal paper are:
http://www.lazertran.com (they have waterslide decal paper as well as silk print decal paper)
http://www.decalpaper.com
http://www.papilio.com
http://beldecal.com