3-D Letters or Logos:

A   B   C
D   E   F

G   H   I
J   K   L

3-D Letters can be made from: 3/4" Wooden Letters, 1/2" Komatex ( Hard Plastic) 1/4" Plastic, 1/4" Aluminum Letters or even 1/2" Hard Foam installed.
Installation can be Pin mounted, Installed with Poxy or even Double sided tape.
It all depends on the surface of installation.