I'm pretty fussy about how I mount drivers, (some would say anal). I've tried t-nuts, wood screws into MDF, nut and bolt and I'm sure some others. Like the look of button head machine screws, but really don't like t-nuts so I've used this several times now with success.
Centering bit for hole location
Gettin' holes perpendicular
Here comes the crazy part. Who knew you could tap MDF? ( also part of the reason for layer cake)
Drip in some Cyanoacrylate (how's that for ostentation?). It's super glue
Let it dry overnight, run tap again to clean up. Slow and gentle.
Baffles were cut oversize so they were easier to work, but didn't want the BB core on the edge so I trimmed and banded perimeter
Round over on the backs using my "mega base" and the vacuum setup from earlier
Here's where we stand now
Next puzzle will be grill frames, stay tuned!