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macmonkey.
That's pretty simple once you figure out the steps, but it will be a bit laborious.
Open a new blank document with a white background.
Activate the Text tool and choose a font and size for your first letter and type it.
Make a new layer under the letter and use the polygonal lasso tool to make a roughly rectangular outline around the letter.
Choose a background color and fill in your selection in the new layer.
Merge the text and rectangle layers you just made.
Use Command T to transform it and rotate it a bit.
If you want add a layer style, perhaps a bit of drop shadow or a tiny bit of texture.
Then just repeat those steps until you've created all your letters with different fonts, sizes and backgrounds.
Move 'em into place using the stacking order to get your overlaps right and there you go.
Ransom Note Effect 
Linear Mode
