Our 5 frame queen cell incubator includes the Ranco ETC-11100-000 Digital Temperature controller for precise temperature control within 1 degree.  It is portable making it easy to transport queen cels  or frames of brood from the hive indoors for grafting in addition to storing capped queen cells or virgin queens until they are placed in mating nucs.  The unit is heated with two 40W bulb in case one were to burn out.  The polyurethane finish protects the outside from wear and the inside from the humidity.  A sponge and/or small container of water (not included) should be placed in the incubator to maintain the proper humidity inside.

Plans for this simplified 5 frame  incubator are available here for those who wish to build their own.
Note: These incubators are currently built to order to it may take up to three weeks to ship.