David Krall asked about how Aeolian fretwork grills were created.
I suspect they were done in similar fashion to the way fretsawn music
desks for grand pianos were made.

This can be seen in a 1926 film from the Bechstein factory. The entire
video is worth watching, but the fretsawing begins at 11:30.

https://www.youtube.com/watch?v=QfemAvrupJ4
 

Jurgen Goering

[ At https://www.youtube.com/watch?app=desktop&v=QfemAvrupJ4&t=690s 
[ Notenpulte werden mit Dekoupiermaschinen in Serian hergestellt.
[ Music desks are mass-produced using decoupage machines.
[ -- Robbie