If you know how to operate the pen tool in Photoshop, then you have a great head start.
If not, or your knowledge is not very great of it, then restructure your knowledge with Youtube! (PEN TOOL TUT-
)
After you have the basic knowledge of the pen tool, outline the apparatus using the pen tool in layer mode.
dismiss the layers pen tool properties now, you can do this by right-clicking the layer the pen tool outline is on, and choose "Convert to smart object", after that right click the same layer, but this time choose "Rasterize Layer". Now its just a basic non-vector flat pixel image.
Now, hold the Control key "CTRL" and move your mouse cursor over the outline layers thumbnail, and now as your holding the CTRL key, click the tumbnail using a Mouse Left-Click.
You've selected the layers pixel boundaries, now poke the eye out of the outline layer, what you will want to do is go down to the images first layer, where the apparatus is, and press "CTRL" + "U" on your keyboard, this will give you a window to re-color the area that the marching ants boundary is selecting.... Move the sliders around until you are satisfied with the color you get (make sure the "Colorize" check box is checked). Done.
Note: make sure you do not select areas on the vehicle using the pen tool that are not supposed to be re-colored, because it will look generic, and very off realism.
I know, the way I explained it may seem a little off to you, sorry if you can not follow... It would be better if I could show you over a dragged out tutorial... But that would be "doing the most". haha
If your having trouble try to message me today and I will try to do it for you.
Hope I helped.