The Domedreamers' Personal Traveler LbNA #17675

When we started letterboxing last year,we read up on the subject and saw somewhere that you should have a separate stamp for exachanges that is different from your trail stamp. So, we dutifully made exchange stamps before our first gathering, and then found out that no one actually does that-they use their trail stamp for everything. However, we share a trail stamp, and had each made an individual exchange stamp, and we decided to keep using them for exchanges. However, some people we've met have wanted our trail stamp as an exchange, since that's the one they have seen. We have obliged, but now we've decided that if people want it, they will have to work for it. So, if you meet the Domedreamers, and you want the dome trail stamp, you will need to answer the following question:

Who invented the geodesic dome?

Hint-he has his own stamp.