Photoshop Wires and Tubes
Here's my version of creating wires and tubes in Photoshop. It's a little different from other tutorials, so I figured I wasn't cluttering the web up with yet another wire tutorial. ;-)
Open up Photoshop and create a new file. Pick whatever size you want, with whatever color background you want.
Create a new layer and call it Wire.
Using the Pen tool 
, draw the shape of your wire.
Click on the Brush tool and select the thickness you want for your wire. I used 19 for my brush.
Select the color of your wire or tube. I used RGB 6/90/129.
Now stroke the path. (Go to the Paths tab and click on the second icon from the left.)
Now that you have the basic wire shape, click on "Add Layer Styles" and select Inner Glow. This will give your wire depth by making the middle of the wire lighter.
Use the following options:
(In the Elements section, the size of you use will depend on the size of the brush you used to create your wire. You'll want a value that is less than the brush size, but not too small. In this example, I used 13px. You may need to play with the settings a bit to get the look you want.)
Underneath the Wire layer, create a new, blank layer.
Click on the Wire layer and merge it with the blank layer. (Ctrl + E.) This "bakes" the layer effect into the Wire layer, so it's as if you painted the effect in, instead of using layer effects. This makes a difference with you do things like erase parts of the layer. You may need to rename the layer back to "Wire" afterwards.
Now you have a basic wire with depth. Ooh. Aah.
One of the favorite things to do with wires is to cut sections away to show the metal under the wire.
Create a layer underneath the Wire layer and call in InnerWire.
Go back to the Path tab and click on the work path you'd created.
Change your brush to a smaller size. (I'm going to use 13.)
Change the color to whatever you want. (I'm going to use a golden yellow.)
Stroke the path again. (Yeah, you can see a big different in how it all looks right now!) ;-)
Add the Inner Glow again, but change the color to a lighter version of your new wire, and change the Size down as well. (For my 13px wire, I changed the size to 9px.) Okay, you can cheat and hide the original Wire layer so you can see your new wire and tweak the effects as needed.
Once you're happy with the new InnerWire, add a layer underneath it and merge the two together like you did for the Wire layer.
Go back to the original wire (unhide the layer if necessary) and erase a few sections. Now you can see the wire underneath.
Now you can add things like drop shadows to the wires for more depth.
I created 2 wires with higher contrast to show the difference between whether or not the Inner Glow is "baked" into the wire before erasing sections of it. Note the dark lines at the edges of the "unbaked" version. That happens because the InnerGlow settings I used start from the center and end x pixels before the edge. Since I erased parts of the wire and created extra edges, the Inner Glow changed accordingly. This gives the impression of bumps in the wire pieces instead of a smooth bulge all through the wire segments.
