I have for some time looking for something to be able to create PDFs and integrate with my current project in Python 3. The usual references are Reportlab or pyPDF. But these two are not yet compatible with Python 3. I do see that since 2010 there has been some discussion about the port in Reportlab, but as of today I can't find any reference to the port.
Another alternative is to use an intermediate format from Python 3 to be consumed in another program, wrapped with a subprocess call. Relatorio does this. I might consider doing something similar or even generate XHTML/CSS and use xhtml2pdf.