The Espanca script (from Castro Verde, Baixo Alentejo, Portugal) is the only complete signary (alphabetical sequence) known of the Paleohispanic scripts. It is inscribed on a piece of slate, 48×28×2 cm. This alphabet consists of 27 letters written double. The 27 letters in the outer line are written in a better hand than those of the inner line, from which it has been inferred that the slate was a teaching exercise in which a master wrote the alphabet and a student copied it.
More information, including a bibliography, on the Wikipedia page