OK I read about some clueless old codger that built his own airplane and did not attach the seatbelts to the airframe properly.

Needless to say, when he crashed, he ate his instrument panel, and from the head injury wound up even dumber than he was when he patched together his airplane.

With that in mind, I embark on the manufacture of the seatbelt installation. We start with this block of greenish material that is just PURE FIBERGLASS. MANY layers, pressed together when wet so that the result is a block of un-imagineable strength, but still good work-ability to shape sand and roughen to any shape that resin will eagerly bind to. The stuff is provided by Lancair in a simple square like you see above, which I will turn into four mounting pads.

OK measure the width of the thing, cut that dimension in half, set your ruler to that dimension, and score the fiberglass.

See? I just scored it perfectly into 4 sections.

Then it is off to the band-saw to saw slowly away...

Into 4 sections...

And now find the center of the glass and use a PUNCH to punch a little hole right in the center of each piece:

And then off to the drill-press to drill in there:

And through we go, making the perfect hole through which the seatbelt attach screw will run:

See?

OK I did it 4 times. Chuck-Norris brownies:

Now a circular scribe is awfully easy to make:

And then sand the edges down on the belt-sander! Easy! (I later learned, though, that it was incredibly dumb of me to wear gloves for this operation. If the gloves had gotten caught between the belt-sander and metal shelf there, it would have dragged my whole hand in. Why they even HAVE that metal shelf there, I can hardly imagine.

And now we have 4 round cookies of incalculable strength with a little hole in the center of each through which to mount the seatbelt attach screw:

Now we counter-sink the cookie so the screw will fit in smoothly, allowing the cookie to make complete contact with the airplane:

See?

And now we put the screw in there! This is what the seatbelt will attach to:

And here we are when done! I had to make one of them a bit different (the pilot's) to fit in the unsual mounting-space available for that seatbelt: