The following are miscellaneous recommendations for Sandboxie settings.

Item 1

C:\Windows\System32\Spool\Printers is typically the folder that stores temporary data for active print jobs.

This is a full access path by default, because the print spooler is not running in the sandbox. If you’re causing this folder to be read-only then you’re probably preventing the creation of new print jobs.
ALSO: c:\windows\system32\spool\drivers\

Item 2

Printer drivers in 64-bit in Windows are 64-bit, and there is a program called splwow64.exe that acts as the bridge between 32-bit programs and the 64-bit printer driver.

In my experiments — and I’ve made plenty — the splwow64.exe cannot load the printer driver inside the sandbox.

Therefore, the only possible workaround was to let the sandboxed program talk to the splwow64.exe outside the sandbox.

Item 3

When I print from my browser (or from the sandboxed PDF application) is Sandboxie accessing the “print spooler” or spoolsv.exe un-sandboxed?

Item 4

This has a small chance of working, but try going into Sandbox Settings > Restrictions > Hardware Access and check the second box to “permit programs to manage hardware device configuration”.

If that doesn’t work, try the checkbox in Sandbox Settings > Applications > Accessibility. I would like to know if this works, but I suggest you enable this checkbox only long enough to test printing, then revert back the unchecked state.

Item 5

Start menu > Devices and Printers > Double click on your printer > Customize your printer

…a dialog box opens

In the dialog box, select Advanced tab, then in the middle of the window, select Print directly to the printer