Using masking tape, tape the bottom of a toilet paper roll/tube closed tightly. (If using scotch tape, it might make sense to decorate the shaker before adding in orzo).
Fill a cardboard tube with the orzo. To minimize the mess, pour the orzo over a plate or empty bowl to catch the falling pieces. Tape the top of the tube closed tightly.
Decorate your shaker with markers, paint, stickers, decals or tissue paper.