I've started drilling holes and attaching cLok fasteners to the aluminum flanges. The installation is really no big deal. They're just like overgrown (and REALLY expensive) nutplates.

Pursuant to the recommendations of Skybolt fasteners, I'm using floating nutplates on the cowling sides and non-floating fasteners along the firewall.

After a fair bit of drilling, deburring and machine countersinking, the receptacles are installed. I touched up the polishing job to remove the inevitable installation scratches before I riveted these pieces to the lower cowling.

The left flange has been riveted to the lower cowling. I used a [sacrificial] machine countersink bit to countersink the holes for the flush rivets. I say "sacrificial" because fiberglass is notoriously hard on cutting tools.

One item of note is that I used the soft AN426 rivets rather than the structural--harder--rivets. The soft rivets are designated AN426A and the standard structural rivets are AN426AD. A Lancair buddy told me that the soft rivets are far less likely to damage the fiberglass when the rivet is squeezed. Aircraft Spruce sells both types.

This is the backside of the right flange. I went ahead and painted the backside before installing the receptacles because I didn't want to tape each one off and I didn't want to just hose them down with paint. The receptacles themselves are actually adjustable for depth so I don't think getting paint in the depth threads would be a good idea.

The one downside to this approach is that my work is very exposed so I had to be careful to minimize my mistakes. I'll just tape off the whole piece when it comes time to start prepping and painting the inside of the cowling. I would have waited to install the flanges, but it became a chicken-and-the-egg problem. I wanted all the final glass work finished before I finished the inside of the cowling.  I needed the flanges installed to do final fitting of the cowling, but I didn't really want to install the flanges until the inside of the cowling was finished and painted... In the end something had to give so I installed the flanges!

Not a fantastic photo, but the next step was installing the cLok fasteners along the firewall flange. You can see where I made the flange deep enough to allow for the installation of K1100 nutplates that I'll used to attach the fuselage skin to the firewall flange. It will [hopefully] be a nice butt-joint as opposed to the really ugly overlap joint in the original cowling installation.

You can also see that the cLok adjustable-depth receptacles allowed me to get each fastener to just the right depth. Very cool and easy to work with.

Now that the cowling fasteners are installed, I can proceed with the final trimming and fitting of the cowling. I'm pretty impressed with the Mustang Aeronautics cowling. This is pretty much the fit as it came out of the box.

As a side note, I'm planning to lay-up a light layer of glass cloth and resin over the rivets showing on the lower half of the cowling. I'm told that if I don't do this, the rivets will eventually come loose and start popping the paint off the cowling. Unacceptable!