Thanks pkr - yes, I've admired all your work and joined the other forum as well so that I could see there!
Beautiful job on the tweeter mounting. My new tweeter bezel is just slightly too large, so I might have to mount it in a similar way without the bezel.
Avoiding self-tapping screws is a particularly noble crusade. They usually bring with them clipped-on 'nuts' that fly off and stick to the speaker magnet during installation, or if they do stay in place, the screw goes beside the hole, or the hole strips out - tighten... tighten, CLICK!, loose. I like the idea of those screw-in inserts with the hex hole. Obviously nice and strong and flush mounting with your recess (done with a flat woodcutting bit?) Clever stuff. Next you'll be mounting the door trim using cam-locks like you put a desk together with?
I must try and find one of those Rivnut guns at a tool shop. This reminds me; speaking of MDF... on my Spider, I found it useful to brace behind the door pull mounting to reduce the flex in the metalwork.
It did give me a smile to see some hot glue getting used after all - I find it useful, though it doesn't adhere to some plastics terribly well. Think I might get some stick-on cable tie mounts instead. As long as they have wheel-balance-weight-grade adhesive tape (******* stuff) they should stay put! EDIT: that word starts with B and is a type of file.
However, having said all that and with the greatest of respect, the acoustics still look like a problem - just look at the big hole in the door metalwork directly above the speaker through which the wiring etc. passes? The sound from the back of the speaker will find its way around inside the door trim and out through the grille along with sound from the front of the speaker. I'm sure you were as concerned as I was...
Standard setup has the grille sealed onto the speaker and grille sealed (?) onto door trim - not very well, but the idea is to get that infinite baffle effect. That's obviously why the standard speakers sound so great... Oh, wait...
My flax-cone 130mm Focal speakers turned up today. I hope to contrive some way to seal the original grille on to the (round) speaker, so that the door trim becomes the 'infinite baffle'. Without that, sealing the holes around the speaker is obviously not possible if the grille is to be used.