Blocked Pixels

1. Open a new document, for this tutorial we used 500x90. Size won't matter. Click D for default colors.

2. Apply Filter > Render > Clouds.

3. Filter > Pixelate > Mosaic
Setting: Cell Size 16

4. Filter > Brush Strokes > Ink Outlines

Settings:
Stroke Length 4
Dark Intensity 20
Light Intensity 10

5. Ctrl+U> >Check colorize > Find the color you like.
Blue was used in this example.