In the last decades  injection-molded polystyrene plastic models--  Consisting of preformed plastic parts which can be bonded together with plastic cement--   have become increasingly popular.and today the model kit market has shifted  to a focus on adult hobbyists willing to pay for more elaborate, higher quality kits.

Completed models can be categorized generally into three classes: kits built 'out of the box', customized kits, and scratchbuilt models.

Models built 'out of the box' are built according to kit instructions, using no materials except those provided in the kit itself.
Customized kits are typically built by more experienced modelers who take a kit and add components, either scratchbuilt or commercial conversion or aftermarket accesories. Such models may be more highly detailed than a straight build 'out of the box' though the trend to more detailed kits is decreasing the difference.
Scratchbuilt models are those for which no kit exists; highly skilled modelers create their vehicle from sheet plastic and components they fabricate themselves.

 Plastic models are available as  Airplanes, Autos, Helicopters, motorcycles, science fiction, Space, Anatomy, historical, Military, figures, wooden, Ships, Anime, Super Hero, rocketry and modeling Supplies from manufacturers such as:

AMT Ertl , Arii , Block N Roll , Brickadoo , Brio , Discovery Channel , Donegan Optical Co., Inc, Down East Concepts, Dremel , E-flite , Elenco , Elmer's , Erector , GuideCraft , Gundam , Haba, Hobby Boss , Kids Label 4M ,  Kotobukiya , LEGO ,  LNL, Manley,  Mattel, Mega Bloks, Mega Bloks: Dragons , Mega Brands America Inc., Miniatronics Corp , Mongo Toys Llc , Olfa Products Group , OWI , Paasche Airbrush Company , Polar Lights, Poof Slinky , Puzzled by Creative Ventures , Queen Elizabeth 2 1-1200 Plastic Ship M , Quest Aerospace , Racing Champions , Revell , Revell Ag (Germany) , Revell-Monogram, RMX  .,Robart Manufacturing, Sababa Toys , StuffJunction, Tamiya America, Inc , Testor Corp., Unimax,  Weller - Cooper Tools .

While injection-molding is the predominant manufacturing process for plastic models, 
 models of minor and obscure subjects are often manufactured using  Vacuum forming  and Resin-casting  Conversions use a kit as a starting point, and modify it to be something else.
Kitbashing is a modelling technique where parts from multiple model kits are combined to create a novel model form .Technological advances have made model-building more and more sophisticated with  the proliferation of expensive detailing add-ons.
Many modellers build dioramas as landscaped scenes built around one or more models. They are most common for military vehicles such as tanks, but airfield scenes and 2-3 ships in formation are also popular.