I was a bit worried when I hacked into the body of my guitar with some inappropriate wood cutting implements that the shape was too far off, but I found a wood rasp (I think that's what you called it, maybe a file) at the back of our garden shed. Who'd a thunk it, but it worked really well.
These first 2 images are the front and back just after it had been shaped with the rasp/file. I'd bought some different pieces of sand paper from 80 grit all the way to 1200 grit to smooth things over. As you can see things are pretty rough for a start.
After an hour or so of shaping, re-sanding, re-shaping and re-sanding. Vola! Smooth as a babies butt! All ready for painting. This time I'm going to take my time with the spray paint and do lots (maybe 4) of thin coats. Depending on now that turns our maybe a clear coat to seal it.