Some materials that seem disposable might be worth holding on to.
The following is by my understanding.
The other day I was handling some polystyrene foam that arrived in a package. Like one would expect, it had been fitted around the package’s contents to protect them from damage. Said product had been unpacked, and the polystyrene remained.
I noticed, as I handled it, how strong it was relative to its mass. I decided to look it up.
It turns out that one-pound polystyrene foam has a shear strength of around 20PSI. It’s a pound per cubic foot.
By way of comparison, Douglas fir has sheer strength of around 900PSI. However, it’s around 29 pounds per cubic foot.
So, Douglas fir has greater shear strength by weight, perhaps by a factor of around 1.5. However, for temporary set-ups, such as forms to hold wood parts in place for fastening, polystyrene could be used effectively.
Source: