Wiktionary
kitbashing
vb. (present participle of kitbash English)
Wikipedia
Kitbashing
Kitbashing or model bashing is a practice whereby a new scale model is created by taking pieces out of commercial kits. These pieces may be added to a custom project or to another kit. For professional modelmakers, kitbashing is popular to create concept models for detailing movie special effects. Commercial model kits are a ready source of "detailing", providing any number of identical, mass-produced components that can be used to add fine detail to an existing model. Professionals often kitbash to build prototype parts which are then recreated with lightweight materials.