Plastic skateboards are made of several different types of plastics and are relatively easy to make in large quantities by using injection molding manufacturing processes. Most plastic skateboards are considered cheap compared to the wooden skateboards.
Still not all plastic skateboards are flimsy or to be considered lesser. It really depends on the type of plastic used. Most riders like a fairly firm board for tricks with only a little give in the center for hard landings and spring action. All Carbon boards and composite construction boards can hold up to the scrutiny of comparison and some riders prefer them.
Skateboard Trucks that hold the wheels are one of the most important components of modern day skateboards. Generally they consist of an axle, triangular shaped hanger and a king-pin bolt. The trucks are bolted to the face-plate, which is bolted to the skateboard.
The king-pin can be loosened slightly to allow for more or less rigidity making the skateboard able to turn easier or ride stiffer for steering. The rubber grommet helps take up the space when a loser setting is chosen. The trucks on both wooden boards and plastic use the same basic principles and strategies however generally speaking the best trucks will be found attached to the more quality wooden boards.
In the future skateboards will be made of carbon nano-tube construction and they will most likely fly; Hover Boards. Indeed, a hover board will not need to have need wheels or trucks and this will save weight and make them much more aerodynamic for flight. Currently the hover boards are large and cumbersome but that too is changing and many new radical designs are in the pipeline.