Start a new document about 600x200.
- Create a new layer
- Use the rectangular marquee tool to make a rectangle selection, size 455px wide and 90 px high. and fill it with black (on the new layer)
- Press CTRL+D to deselect.
- Now apply gradient layer style(Layer->Layer Style->Gradient Overlay) to this layer, using this setting:
-Create a new layer
- Make a selection similar to the one shown below.
- Then fill it with black, then CTRL+D to deselect
Now CTRL+Click on "Layer 1" (the first layer), while have the "Layer 2" selected as the working layer, go to SELECT->INVERSE , then hit delete, this will load the original size, and delete the black around it.
Now use the polygonal selection tool and make a similar selection on the black.
Then hit DELETE, to delete the black selected area.
Now use the rectangular marquee tool and make a rectangular select at the left similar to the image below, then fill it with black. We are making the GRIP for the lightsaber
Thats your basic shape for the lightsaber. now use the selection tool and select the following and hit DELETE on "Layer 1" and 2 to delete the black and bottom layer.
Now, you may want to play around, adding a few more bumps and grooves onto the handle, i'll leave that up to your creativity, we'll jump to create the blade now.
Create a new layer at the bottom of "Layer 1" (just above the background layer).
create a rectangular marquee selection, like below and fill it in with a color. You will need to resize your document to wider if you want to see the WHOLE blade.
Now apply the following layer style to the new layer. (Layer->Layer Style->...)
Now, fill the background layer with a dark color, and your lightsaber will look better.
The following image, I added a few more patterns and shapes onto the handle. If you want to know what i've done, Download the .PSD file
Be creative.
More Tutorials: 
