%
% Take the A5 landscape dottes.pdf and produce a second PDF
% formatted for A4 portrait, which two pages per A4 page,
% and ordered for booklet printing.
%
% Print the resulting PDF with long side duplex.
%
\documentclass[a4paper,final]{article}
\usepackage{pdfpages}
\usepackage{ifpdf,ifxetex}

\begin{document}
\includepdf[pages=-, nup=1x2, booklet=true]{build/dottes.pdf}
\end{document}