I haven't found it locally, so I was hoping to order one online.
The hole in the compressor and the hole in the copper pipe is 3/8", so thats what I am looking for. Probably 2-3 feet will do the job. Will have to check harbor freight again.
My air lines are very simple 1/2"copper water pipe from lowes. I used it because I know how to do copper, and you guys seem to think PVC is just a bomb in waiting.
My drain is already set up with 1/4 inch tubing left over from the a/c install.
Ummm, if I have the picture parsed correctly, you have a 1/4 inch copper extension coming off the drain valve of your compressor?
That's fine and good.
But you have that copper extension touching up against the shell of your water heater. You also have the wooden platform your air compressor tank is sitting on ALSO touching up against your water heater tank.
Move or rearrange things so they are not touching.
Dissimiliar metals touching = bad
Vibrating things touching = bad (keep your mind out of the gutter for now

)
Also, don't 'choke' your airflow down by running a 1/4 inch hose whip. 1/2 inch hose with 3/8 NPT fittings is better.
(also, keep in mind that the fittings are almost always NPT, which do not 'measure' on a 1:1 basis with a ruler. ie: 3/8 NPT fitting/hole is NOT 3/8 inch in diameter. Make sure you get the right size fittings/adapters.)
btw, a good

for running your airlines in metal. 1/2 inch copper should do just fine for a relatively 'short' run of air line for 'moderate' air flows. But I usually go for overkill, so I like to run the hard lines as 3/4 inch for the main 'trunk' line(s) and then maybe tap off with 1/2 inch at some stations (or just tap off at 3/4 inch and put reducing bushings/fittings for the quick-connects to attach to.
Also, bigger pipe acts as a bigger air resevoir as well as flowing more air (if you compressor can keep up) and gives more exterior surface area for the air stream to cool off after being compressed.