Surfing across the web, I often find tutorials on DIY equipment stating that it is made of plywood. Very often, the images shown on these tutorials clearly demonstrate that the author has actually used chipboard or another kind of material. There are many different types of wood one can get, but, in general, they can be put into 3 categories:
Chipboard (or particle board in the US) is an engineered wood product manufactured from wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded. Particleboard is a composite material (definition from wikipedia). It is usually found in widths of 10, 12, 16, 18, 19, 22, 25, 28, 38 and 58mm. In general, it is not used for furniture, although there are some parts for which it is preferable. The corners of this material are sharp and are mostly covered with a plastic tape.
There are high and low grades of chipboard. You can find different grades under different names, such as flakeboard, waferboard, fiberboard, hardboard, pressed wood etc. The price depends on the density and the quality of the board. If you select a reasonably dense and thick board, it will withstand a lot. I am making my plyometric box out of 18mm thick chipboard (next post).
As an example of a material often separated from particle boards, “Mediapan” is a commercial material made of finer dust and it is compressed more than usual boards. Also, it is produced in smaller widths (starting from 3.2mm). You can use it for more heavy-duty applications – in crossfit DIY you could make, for example, wooden rings. It is quite easy to repair, whereas the usual kinds of chipboard aren’t so.
Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured. Plywood is used instead of plain wood because of its resistance to cracking, shrinkage, splitting, and twisting/warping, and its general high degree of strength (definition from wikipedia). Using thick plywood, you can build any piece of equipment you’d like. However, it is more expensive than particle boards, so use it only if you must (or want to). There are visually very distinct types of plywood, depending on how the layers are stacked and how thick they are. Sometimes the layers are stacked, but the wood is not cut perpendicularly to them or in parallel with them. One then gets the impression that the plywood is in fact hardwood, but this is not the case.
Finally, there is hardwood (and softwood). It is wood from angiosperm trees (It is a word that may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen). This is just a piece of wood, not commercially produced or pressed into boards (although often cut into them). You will almost never need hardwood to build your equipment.
I hope this makes some distinction between different types of wood you can get and helps you choose more easily when you need to build something out of wood.