The body is solid birch, as is the rest of the guitar. The "binding" is painted on. This shot shows the "pyramid style" bridge, which appears, at first glance, to be made of ebony or some black painted wood. It is, in fact, made from cast aluminum - as is more apparent in this close up shot. Here is the back. The peg head sports an Oahu logo decal, and also has the tuning buttons reversed so that the instrument can be tuned while sitting on the lap of the player. Although the guitar was probably made by Regal, it has an Oahu brand (literally burned into the wood) showing under the soundhole.
The Oahu Publishing Company was one of the leading exponents of the Hawaiin music craze that swept the nation from the late teens until well into the 1930's. Their literature stressed that they considered themselves a music distributor - among the their products were regular (Spanish) and Hawaiin guitars, lap steels and sheet music. It is generally thought that Regal manufactured most of their musical instruments, but that has never been definitely established as fact.