Creating a dirty, rusty interface requires a great attention to detail. One of the many things you have to be sure of is that you have lot of details and gadgets on your interface. This tutorial explains how to create a nice little speaker.
Create a new channel. Using the Pencil tool, draw two vertical lines 4 pixels in size. Using the Rectangular Marquee tool, make a selection around the lines.
The size of these lines will define the size of the cells in the speaker's mesh.
You will also need to have Base Rust texture (or any other rusty texture) ready for the tutorial.
In the main menu select Edit > Define Pattern.
This will save the selected area as a pattern for the Fill command (and for the Paint Bucket tool).
If you still have a selection active, remove it by pressing Ctrl+D. In the main menu select Edit > Fill and the Fill dialog will popup. Set Use to Pattern and click OK button.
This action will fill the entire channel with the pattern. Resulting image will look like a grid.
Apply Ripple filter (Filter > Distort > Ripple) to the channel with the grid. Set amount to 25 and Size to Medium.
By applying this filter you will make the mesh look damaged and old which is a must have effect for any rusty-dirty interface.
Makea circle selection in the center of the image using the Elliptical Marquee tool (hold the Shift key while selecting for a perfect circle). Intersect selection selection of the circle with selection from the mesh channel (Ctrl+Alt+Shift+Click on mesh channel's icon in the Channels palette).
The size of the circle selection will define the speaker size.
Make the layer with the texture active in the Layers palette. Add mask to the layer by clicking on the Add Layer Mask button in the bottom of the Layers palette.
Add Bevel and emboss layer effect (Layer > Effects > Bevel and emboss) to the mesh layer as shown in the picture.
This is what you should get after completing steps 6 and 7.
Chose the Airbrush tool, set Pressure to 10-20%. Select any of the nature brushes. Reset colors (press 'D'). Click on the Mask's icon of the mesh layer. Experiment with the Air Brush on that mask to get some cracks and/or bumps.
Add some final touches and you have one nice speaker for your interface!