space domes missing

This is the Miniature Apollo Exploration Set as it appeared on Etsy. These cool sets came boxed and had many parts as you can see.

These included two small white plastic domes with a black and white hatched band on the larger one - above right bottom. They also appear to have a small nipple on top.

Here they are in the Sears catalogue.

These two domes are missing in my set and I have been thinking what would make a suitable replacement. Has anyone got any ideas?