newberg

Wow, what a wonderful creation!
Having worked with decoupage for many years I might consider either a decoupage medium or diluted white glue for adhering the egg shells. Because both dry clear you can layer many coats without distorting the material you are working with. Dry between each coat, 12-24 hours. After 3 or 4 coats I would diluted white glue (a tad bit less water this time) and fill the spaces between the shells. Again this will dry clear will build up those areas lower areas allowing for a smooth finish. Add as many layers of water base varnish as you can tolerate with light buffing between coats. The trick with decoupage, after mastering the cutting technique, is patience. It's the multiple coats of varnish applied evenly and allowed to dry thoroughly between applications that gives the material that "old, always been there" look.
Jeffery you are a genius. Now I know what to do with a set of tacky pseudo brass dinner chargers that I have. I think this technique will make a beautiful set that I'll use more often.
Thank you for sharing!