tiny chicken eggs

when my hens get ready to take a break from laying,they will lay tiny eggs for a day or two or what I like to refer to as chicken pharts....nothing in them but air or egg white. I've collected 6 so far. Biggest is apx.2" long & 4" around,measured like a waist line. I'm trying to figure out a craft use for them. Prefect for small doll heads(Eggbert/Eggberta dolls) but since they're so small I'm afraid if I try to drill holes to blow out whatever might be inside they might break in the process or make the shell too weak for use.I only get a few a year so I don't want to break any.

Your sggestion would be appreciated.

P