snow drum

In its simplest form, a snow drum is a cylinder with 3/4" plywood ends, 18-24" in diameter, and hardware cloth (rabbit wire mesh) with holes 1/4-1/2" forming the circumference. A pipe runs horizontally through the center and acts as an axis. Once the drum is filled with shredded polyethylene flakes (artificial snow), rotating the drum causes the flakes to work through the openings in the mesh and fall to stage.

A much more elaborate and costly unit is manufactured by City Theatrical, and has DMX control.

DMX Snow Machine for Stage, Display and Film Projection

For a full stage effect, a snow cradle is usually preferred, as long as the venue has a counterweight fly system with two adjacent linesets available. See also the site http://www.fxtumblers.com/.