Abstract: A megaphone is formed from a self-supporting flexible plastic sheet. The sheet is wrapped with overlapping side edges to form a horn shaped member. The overlapping edges are releasably interlocked by edge slots and interconnecting edge arms. A separate mouthpiece has a tube which telescopes into the narrow mouth end of the horn and has an outer shaped end for coupling to the user's lips. The plastic sheet may be rolled into a compact tubular roll. The mouthpiece is placed over the roll to maintain the rolled configuration for storage and transport. The horn sheets can be readily mass produced by stamping and the mouthpiece by molding.