My intention for the video was more about the composite construction technique than the exact components that they used ... and the technique could benefit PVC construction as well. We have been using composite construction on aircraft for years. Composite construction components are even used on USAF fighter planes. As the guys in the video said "very light weight
and wicked strong". .
While half inch EPS foam and fiberglass screen is plenty strong for cabinets, I might favor 1/8" plywood glued to the top and bottom of slightly thicker EPS foam (3/4" or 1" ??) for bunk beds construction? You could still paint
the plywood with Glidden Gripper paint
and embed fiberglass screening into the paint
. If that still isnt strong enough, you could put a fender washer on a longer drywall screw and run that from the top down into a 1x2 pine/oak stiffener on the bottom side. If needed, you could coat the pine stiffener in glue/paint and fiberglass screening. That construction should still be very light
weight and very strong!
Fiberglass is strong in tension (i.e. bottom of a weight-bearing part); 1/8" plywood may add strength in compression (i.e. top of a weight-bearing part) as well as strength in tension.
If supporting bunks with PVC posts and frame, coating most of the pipe with Glidden Gripper (or clear-drying glue?) and then wrapping fiberglass screen material around the pipe could keep the pipe very straight and be stronger than PVC pipe alone.
The thicker the composite sandwich the more it resists bending when used on longer lengths/spans.
In addition to being strong and lightweight, this kind of construction is relatively inexpensive. If you are unhappy with a result, throw it away and make another.
As they say ... "Your mileage may vary."
If you use the composite construction method, maybe you could send results and pictures of your finished project?
Again .... Best of luck!