There are many things you can do. Cockpit glass and windshields can easily be made from the clear plastic containers fruit like blueberries and strawberries come in. Instrument panels can be as simple as printing out a dashboard and gluing it on a panel or as intricate as hand painting gauges and such. Seats are easily carved from foam and painted or if your really into detail using normal foam and covering it in cloth.
Then there are things like air brushing which I am just getting into.
then you can go really all out and do things like
@willsonman or
@rockyboy and
@wilmracer do. look up any of their big builds and you can learn some serious tricks and really cool things that can be done.