Another filament box with gentle heat to help keep filament dry.  You can just store filiament in the box with the warmer, and/or feed directly from it as it has a roller to spool smoothly and a hole for the filament to exit.  Also a notch in the back for heating pad wire to enter. 

I used this heater off of Amazon “Heating Pad,Electric Cloth Heater Pad Electric Heating Element Film Carbon Fiber Heating Pad”.  Two heating pads for under $10.