There are a number of general components that are useful for testing while you work out what you’re going to be able to fit into your vehicle. Something like jumper wires and solderless breadboard allow you to quickly try out prototypes while a good stock of resistors and transistors can allow you to quickly figure out the best configuration to drive the LEDs on your model. In addition spare Arduinos and motor drivers with headers soldered on so that you can push them into breadboard make it very easy to test a design before you start soldering.