You can probably find a simple PDF export function in TurboTax with which you can make documents from your tax return forms. Other than that, you can always try virtual PDF printer.
Convert TurboTax 2012 tax return file to Adobe Portable document format.
We found 2 software records in the database related to .tt12 to .pdf file format conversion.
Microsoft Windows software - convert tt12 to pdf on Windows
A tax preparation software developed by Intuit
Convert from tt12 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned tt12 to pdf. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert tt12 to pdf on OS X
Popular tax preparation software