Focus on The Bride Stripped Bare by Her Bachelors, Even and explain the Duchamp's methods.
I bought two plate-glass panes and started at the top, with the Bride. I worked at least a year on that. Then in 1916 or 1917 I worked on the bottom part, the Bachelors. It took so long because I could never work more than two hours a day. You see, it interested me but not enough to be eager to finish it. I'm lazy, don't forget that. Besides, I didn't have any intention to show it or sell it at that time. I was just doing it, that was my life. And when I wanted to work on it I did, and other times I would go out and enjoy America.
The Large Glass...was gradually assuming the mysterious aura of a famous work of art that hardly anyone had seen. Duchamp's efforts to finish it became more and more sporadic. For six months the Glass lay untouched in the studio, gathering a thick layer of dust which Duchamp then proceeded to use as a pigment, gluing the dust down with varnish to one part of the "bachelor machine" (the "sieves") and wiping the rest away. This gave him a color that did not come from the tube... To arrive at the shapes of the "draught pistons" in the Bride's "Milky Way" (terms from Duchamp's own notes), he made use of the wind: he suspended a square of gauze in an open window, photographed it three times, and reproduced the wind-blown shapes at the top of the Glass. The placement of the Bachelors' nine "shots" (which never do reach the waiting Bride) was effected by dipping matches in wet paint and firing them from a toy cannon at the Glass. The forces of gravity, wind, and "personalized chance" were thus substituted for the workings of his own conscious hand, always in the spirit of hilarity that Duchamp once paraphrased as that "necessary and sufficient twinkling of the eye," and always with the same meticulous, painstaking attention to detail that a scientist might apply to a controlled nuclear experiment.