For printing a question together with all answers, the best option is still the same as two years ago: use Stack Printer. There is a handy bookmarklet on that page, which allows any question to be saved as PDF directly from the question page. The quality is pretty good.
Or, if you want the Q&A to be formatted just the way you want it, try Save Q&A as LaTeX, which converts the question with answers (and optionally, with comments) into a file that can be copy-pasted into, e.g., writeLaTeX or any other LaTeX compiler. Then get PDF from that. Some conversion errors may still occur; they require a minor manual adjustment of the source.
(I mention writeLaTeX specifically because this is the environment I use for testing the correctness of conversion in Save Q&A as LaTeX. This project is still under development.)
Disclaimer: free version of StackEdit no longer offers saving as PDF
For saving an individual post (question or answer): an improved version of the workflow suggested by Sergio Parreiras:
- Click to edit the question/answer.
- Copy and paste the contents to StackEdit
- Click cancel to close the edit.
- From the
# menu on the left, select Save as PDF: