Robert's Musical Restorations makes and sells snare drum beaters and
bass drum beaters, as well as other items that can be used in a band
organ. See http://robertsmusicalrestorations.com
There also exist building plans for the Wurlitzer 104 and 105, by
R. M. Stanoszek, and Wurlitzer 105 building plans by Randy Alien
(firstname.lastname@example.org (delete .geentroep).
I bought a snare drum beater on eBay from Roberts Musical Restorations
a few years ago, when I too was thinking about building a 105. The
beater was a fine hand-crafted item, far better than what I could have
done. When I decided to go another route, I resold the beater on eBay.