[NXSTUDIO-DRUMMER]

Regarding your grills,
First of all, the project is really turning out nicely. 

Condensed version of my earlier message. Fishboat, If your grill frames entail resonance issues, or rattling against front baffle, I used this product below successfully, on some old subwoofer cabinet grill frames, that rattled on the front baffle.

Perhaps not the ideal solution, but it was what I had laying arouond in my drumstick bag, and worked great. Hmm, what resonates more, grill frame or drumhead?

Here is one example that worked for me, just cut to size.
https://www.guitarcenter.com/RTOM/Moongel-Percussion-Dampening-Gels-1274115039839.gc









Enjoying following your build 

[fishboat]

Thank you, and thanks for the suggestion Drummer.  Looks like good stuff and it would work. If I hear any rattling, I'll order some up.

Speaking of drums..I've been listening to a lot of Manu Katche lately in his collaborations with Jan Garbarek, Tomasz Stanko, Marcin Wasilewski... on ECM.  Heck of a drummer.  Fun to listen to. (Listening to "Live in Concert" 2104 at a club in Paris right now..he cuts lose more on this than on the ECM albums)

[NXSTUDIO-DRUMMER]

Thank you, and thanks for the suggestion Drummer.  Looks like good stuff and it would work. If I hear any rattling, I'll order some up.

Speaking of drums..I've been listening to a lot of Manu Katche lately in his collaborations with Jan Garbarek, Tomasz Stanko, Marcin Wasilewski... on ECM.  Heck of a drummer.  Fun to listen to. (Listening to "Live in Concert" 2104 at a club in Paris right now..he cuts lose more on this than on the ECM albums)

Manu is a excellent drummer,
Here's a visualization, of what goes on behind a drum kit performing. Do your self a favor and open up your computer screen to full view, to truly get a full appreciation of what us drummers go through.  
https://www.youtube.com/watch?v=xlvbY6DToPs

[fishboat]

Crazy video.

I couldn't do it. Even when I was young. No idea how drummer's survive playing for years and years. I'd think repetitive motion issues would eat them alive.

When I was a young man in high school Billy Cobham and Alphonse Mouzon were all the rage in our circle of friends, and have listened to the now old-guard (hard, be, post) bop drummers ever since. Rock drummers..that's a whole nuther book.

I was a Zappa fan too..saw him 5 times, often in Chicago on Mother's Day.

Interesting:
https://www.youtube.com/watch?v=xGeZGrJ1ICQ