Wear a dust mask and wrap-around eye protection. Work outdoors or in a well-ventilated space to prevent antler dust buildup.
Make a few passes with the coarse sanding belt over the entire antler to smooth out any ridges. Repeat with the medium sanding belt.
Wipe down the entire antler to remove sanding dust. Look at the antler and decide where you wish to put your scrimshaw. Use the fine sanding belt to smooth an area just large enough to accommodate the picture you wish to create. Wipe the antler dust away again using a soft cloth and a little rubbing alcohol.
Use the extra fine sanding belt to smooth the sanded portion of your antler one last time. Attach a buffing wheel to your power drill and buff the entire antler. Wipe the dust away one more time.