how to make N-up PDF with free software

The main benefit of N-up is to cut paper costs. For example, you can cut down your paper cost by 50% with 2-up printing / copying, and 75% with 4-up printing / copying etc. This feature is also useful for producing handouts and presentation notes.

some printers support N-up printing, but I just want to tell you a N-up software,

Usage: java nup_pdf [options]

infile : input PDF file
outfile : output PDF file
pages : number of pages per sheet. pages = 2^n * x^2

Options:
-b : draw bounding boxes
-m : outer margin (measured in points)
-s : spacing between pages (measured in points)
-k : 0=n-Up, 1=Booklet

(C) 2005 Marcus May (QuoVadis/NBS)

it bases on iText, you can download

PDF N-UP Maker,compiled by gcj, does not jvm, only windows console version
nup_pdf.jar, java version, can run at windows, linux, Mac OS X, need jre1.4 or over
nup_pdf.java, source code, from qvPDF.