Sometimes I will rework the body and add wiring to the engine.
Or make new wheels instead of just swapping them.
This one has a stock body but features a scratch-built engine, detailed interior and wire wheels.
But usually I just repaint and add painted detailing of the molded in details.
Nearly all of my HW customs feature custom designed decals.
They are also used to test new paints, like the pearl white and pure blue Tamiya LP lacquers this one sports.