<p>I'm working on a project using 3D printed parts, everything is working very nicely except for one part that needs a 3 mm x 1.2 mm diameter rod. I can print with PLA/PLA+ but such a thin object doesn't seem viable for 3D printing. Is it still possible or am I better off using a 1.2 mm metal dowel?</p>
<p>The bigger part (5 mm x 7 mm diameter) near the back isn't an issue, it's the small rod that I can't seem to print correctly</p>
<p><a href="https://i.stack.imgur.com/JGkft.png" rel="nofollow noreferrer" title="Part"><img src="https://i.stack.imgur.com/JGkft.png" alt="Part" title="Part" /></a></p>

It would be impossible to print this standing with the rod straight up, and even if you got it to print the part would be very weak due to the thin cross-section of the rod aligning with the layers.
The only way to print this part and get a usable result is to print it in the orientation shown in the picture, with the rod part being horizontal. Because the layers will now have a much larger cross-sectional area, this not only makes the print much stronger but also prevents issues with the plastic not cooling off sufficiently between layers. Though this will still be a tricky print, because now you'll need lots of support material.
Using a metal rod is probably the better option. Another option is printing the rod lying flat on the bed, and gluing it in place later. This would avoid the issue with support material.