It is still necessary to print documents. Many printers are able to print one side of the sheets, here I describe the procedure to print both side correctly. The procedure depends on the kind of printer.

Make an empty .pdf page:

$ echo '' | ps2pdf -sPAPERSIZE=a4 - white.pdf

Add an empty page at the end of a document:

$ pdftk  W=white.pdf D=input.pdf  cat D W  output output_file.pdf

Extract even-numered pages from a document (replace the word even with odd for odd-numered pages):

$ pdftk  input.pdf  cat 1-endeven  output_even.pdf

Reverse the order of pages:

$ pdftk  input.pdf  cat end-1  output output_reversed.pdf

Being PPPP the printed face, and WWWW the blank face it is the case 1 if printing a three pages document the sheets end up like this:

  PPPP
3 WWWW

  PPPP
2 WWWW

  PPPP
1 WWWW

In other words, the printed pages end up with the face up and the order of the sheets is reversed.

1. Ensure the input file has a even number of pages adding a blank page at the end if needed.
2. Split the file in even and odd pages.
3. Reverse the order of the even and odd pages file.
4. Print the reversed even file.
5. Put the printed sheets back in the printer being careful to align the printing side and top side.
6. Print the reversed odd file.