A rotary machine including a substantially vertical rotatable drum having pellet-receiving receptacles in its peripheral sidewall. Gravity causes pellets to collect toward the drum's bottom. As the drum rotates, pellets received in the receptacles are carried upwardly from the bottom. A printing device positioned within the peripheral sidewall prints indicia on the inwardly exposed surfaces of the pellets. Optionally, the receptacles define apertures extending through the peripheral sidewall, and a printing device is positioned externally to the peripheral sidewall to print indicia on the outwardly exposed surfaces of the pellets. Drilling or inspection devices may be provided in addition to, or instead of, the printing devices. A support member may be provided adjacent the peripheral sidewall to prevent gravity from causing the pellets to exit the receptacles. Chutes may be provided to supply and remove pellets to and from the drum. An air stream may eject pellets from their receptacles.