: Think the "particle" board or "flake" board referred to
: here may be "MDF" medium density fiberboard. It is much higher
: quality (and sligtly {50%} more expensive) than regular particle board and
: could be good if laminated for this purpose.

MDF is a brown material made of very fine fibers. it is very uniform in color with no visible texture.

OSB is Oriented Strand Board. Sometimes called "Aspenite" or flakeboard it has large chips of wood (1" square or larger). It is very similar in color to plywood but very motled.

Particle Board is somewhere in between. It has small but visible particles of wood (about 1/16") it is light tan in color. The color is quite even.

MDF and particle board are not very structural. Partical board in particular can be quite brittle. MDF seems a little tougher, but is still not very strong. Both are quite good for forms being dimensionally stable and fairly easy to cut. Ther are not great for strongbacks because of their brittleness. I've made several boats on a particle board strongback. It was very stiff, but a sharp blow could break it clean in half.

OSB is similar in properties to CDX plywood but having some of the properties of particle board. It is tougher than particle board but more brittle than plywood. Unlike cheap plywood, OSB does not tend to have voids so it can be stronger in some situations. It can be used for forms and is pretty good for box-beam type strongbacks. It tends to be a little cheaper than plywood.