This one will keep you thinking!

[Rodgera]

First looks can be deceiving

Optical Illusion Alphabet | A woodworker's dream (http://feedproxy.google.com/~r/OpticalIllusions/~3/Emb6GXQiRyE/optical-illusion-alphabet.html)

Then the penny drops.

[Woodkid]

That was easy haha :U

[joe greiner]

Cool.

Here's an entrance sign to California State University at Northridge, made of pipe, and viewable from two directions. IIRC, the letters are about 10 feet high. Each letter is square in plan, like this: <> <> <> <>.

Cheers,
Joe