Hi Vinod,
Prusa i3 by far is most commonly built rerap printer and there are tons of details/guides available in the internet. Starting with, you might want to refer to the reprap wiki for more details:
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[
reprap.org]
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There is also a good video tutorial about assembling and building prusa found here:
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[
www.youtube.com]
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I was not able to find the complete playlist of this guy, but its pretty good to start with.
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Arvind