I got the GPO-3 fiberglass sheet from Online Metals dot com. I hoped to substitute it for the more expensive G-10. Looks like it worked. It is smooth like G-10 though in the picture above it looks rough.
This 2 foot by 2 foot sheet was $10.  Picked it up myself.  Compare to same size G-10 at McMaster Carr at $47 plus some $20 shipping.
The red probably means it is phenolic.  Both of these are fire resistant.

The panel looks like it was made with chopper gun, but it will be used for low load applications, so no worry.
They did used to be a friendly neighborhood supplier. They have been bought by Thyssen Krupp and have a new corporate bureaucracy feel now. Good prices though.


When Not To Use VHB Tape

VHB tape is wonderful stuff to stick things together. It was created for attaching windows to things, with no fasteners. However, I just had an illustrative example of when not to use it.
I was very impressed with the VHB tape on the lunar lander dome. It had a steel frame to stick to.  Straight and smooth.
Maybe out of inertia, I also put it on the little triangular windows of the lunar lander. Later I realized the tape looked too wide on those tiny windows and I vowed to trim it back when I bought a tall enough ladder to reach.
I got the ladder.  It turned out that all I had to do was push a bit and the windows folded back in. So I could then remove the tape.
Two lessons. For VHB tape to work well, the contact surface must be both flat and smooth. Many of you can do that. I seem to not have that skill nor ability in hard to reach places.
The second lesson is the VHB tape must be kept dry. Due to no ladder, I could not protect it with my caulk.
My triangular windows are now stopped in and bedded with caulk.  The caulk can span the sketchy surface and gaps.
If you can do and flat, fair and smooth contact surface, go for it. If not, use adhesive caulk, like the System 3, two part polyurethane.

In contrast, I have a solar powered motion light stuck above the front door.   It was stuck on with a couple of strips of VHB tape.  Turns out the light is defective and won’t work.  I not only can’t  remove it, I can hang from it.  And swing.  Gonna take a chisel maybe.