Intuos 3 Drivers for Mac OSX Sierra (10.12) I have an old Wacom Intuos 3 tablet (with pen and mouse) that I occasionally use with my Mac (OS 10.12.6 - Sierra).
I noticed my Wacom Intuos 3 mouse was acting strange (clicks not always being registered). I tried to re-install the Wacom Drivers for the tablet to troubleshoot whether this was a hardware (mouse itself) or software (drivers) problem.
When I reinstalled the latest drivers that work with Intuos 3 tablets for Mac (Driver 6.3.15-3), the Wacom Preferences Pane kept saying there was something wrong with the driver and the computer needed to be restarted, and if the issue persisted to re-install the driver. I restarted my computer a few times and still had the issue, then I un-installed and I re-installed the driver and still had the issue.
I realized it was probably because the supported Mac OS versions were 10.8 - 10.11 according to the Wacom Driver site and searching &quot;Intuos 3&quot;. I was running Mac OS 10.12.6.
I then tried installing the most recent drivers (Driver 6.3.37-3  for macOS 10.11 - 10.15) because I thought that might work with my newer Mac OS, and after installation the Wacom Preferences Pane kept saying there were no devices attached, even when my tablet was plugged in.
How do I get drivers for Intuos 3 that work with Mac OS 10.12? It used to work just fine, but now with no working drivers, my tablet is not mapped to my screen properly and using my mouse/pen is terrible.
After searching all over the internet, I found a few people who have the same problem here.
They said to use Wacom Driver 6.3.8-2 (macOS 10.7 - 10.9).
This driver can be found here.
Alternatively, you can find the link to this driver by:

Navigate to Wacom's Driver Search Page here
Search for &quot;Intuos 3&quot;
In the MacOS driver box, select the &quot;Older Versions&quot; link
Scroll the list until you see Driver 6.3.8-2 (macOS 10.7 - 10.9) and download it
Un-install any previous non-working versions of the wacom tablet driver and install the newly downloaded version

After I installed it, I was able to see the Wacom Tablet on the Preferences Pane and edit the preferences to map the tablet to my screen size again!
My pen and mouse work as they did previously, but the original issue with my mouse (clicking) now appears to be a hardware issue. I will go buy a replacement mouse from eBay.