I also polish my emu eggs with my dremel. After I get to the level and shade I want of the egg...I smooth all the bur marks made by my high speed dental drill, with flexible dental discs starting from coarse to medium.....sometimes to fine and extra fine also. Mainly I use the Coarse & Medium..they come in sizes 5/8 and 3/8 and use a special mandrel to attach the discs.
In the areas that the discs do not reach..I use a brownie point. They will smooth to a satin like finish..but they do not remove bur marks. You would have to use a green or white stone for that in the tight areas if necessary. (The green stones are equivalent to coarse discs and the White stones are equivalent to medium discs.) When I have the egg completed..I use the UV-resistant spray to maintain the colors on the emu egg.
Start by drawing and oval the size you want on the shell with a pencil. Sandpaper, smaller the number, the coarser the sandpaper. Start with the smaller number and proceed to larger numbers. I use 50 grit sandpaper on a random orbital air powered sander that takes 85-90 bls of air pressure. Sand with this grit until you get to the white layer of the shell. Change to 150 grit and do this for several minutes to get the scratches out from the 50 grit paper. May need to look under light or magnifier to see if the scratches are gone.
By hand: wet/dry sandpaper cut pieces to fit the palm of your hand. grits are 240, 320, 400,600. Put the shell in sink half filled with water, get sandpaper wet and start sanding by hand. Start at 240 and work up to finish with 600. At least 5 mines with each grit, keeping water on as you sand.
When finished, dry the shell and the next step will be to polish it so it will be very slick. Cloth buffing wheel with polishing compound (found at knife-making stores). Always move shell around, If you stop the shell in one place too long, you can get burn marks on it. Continue until shell feels very slick.
Do the bleach treatment next if not done yet. After cleaning is done, spray a coat of clear acrylic sealer on the oval and let dry, then sketch the design you plan to do and proceed.
I carved it with diamond bits- first time I've used them dry. It was easier to see clearly what I was doing when I used them dry, although in some cases I used them wet when I wanted a smoother finish. I did most of the carving after the scrimshaw was finished as I didn't know how fragile the egg would be once it was carved.
I sanded down the egg and polished it on a buffing wheel before I did the scrimshaw. I didn't get past all the pores, but I think the little black dots add to the old fashioned look. The actual scrimshaw was a little more difficult than on ivory, but after a while I got the feel for it.
I made the little ship from scratch. It doesn't show up very well due to poor lighting- but I guess you can get the idea. I ended up putting foam core as a base and a thin layer of texturized plaster of paris over that. It is painted in a dark dark blue since there was no other color on the egg and I wanted to keep that monotone effect.