|There is no way to print a book for free. You can publish an eBook (bits) free if you don’t count your own labor. But to go to print requires paper and toner or ink, a binding to hold the pages together, and shipping costs to mail the heavy book (atoms) somewhere.|
One method is to go to https://www.createspace.com and follow their guidelines. This is not a free option, but going from bits to atoms will cost money because of the consumables used in the printing process.
Another site that helps is http://www.blurb.com. Again, not free.