A Christmas tree machine is a concept in science fiction referring to a modestly sized device which, given a few raw materials, can produce almost anything imaginable, and in great volume. (Thus, for the owner of such a machine, it is always "Christmas morning"). A Christmas tree machine may be a nanotechnological molecular assembler, or a highly advanced 3D printer, or be based on as-yet unknown technologies.

The term "Christmas tree machine" is often used with satiric or ironic intent, as in science fiction writer Charles Stross' Tough Guide to the Singularity.

Numerous examples of Christmas tree machines exist in recent science fiction:

  • Star Trek's Replicator Machine