I visited my friend George, he is a handy man!
This is his garage, sometimes accidents can happen?
Took 2 photos, one with george the other without George to get accurate background.
Edited George and removed his head and copy/pasted head to his hands.
Copied background photo and merged all copies into one.
Applied smudge brush to blend the blood-thirsty bits and hand painted collar etc.
Finally duplicated image, selected filter-find edges-desaturate to blend-out unwanted detail.
Cleaned up image, lighting detail and shadows... (note: head shadow also removed)
Then framed it and flattened, sized and posted! ... simple as that... no science at all really?