Looking good! The hardware store light dimmer switch is always a cheap alternative to the expensive dimmer switches sold as reptile specialty items.
As an added safety you may want to get an electrical box to house the switch and wire nutted wires. Most boxes will have clamps that hold the incoming wires on each side. I've seen a couple unsecured wire nutted wires come apart under load by a little bit more tug than usual and cause all kinds of arcs and sparks sometimes ending with a blown breaker or fire, sometimes starting a fire late at night, and other times just coming apart with no other ill effects.
Not to worry man, my technical advice comes cheap!

On a side note I am having way too much fun with the new smiley face stuff!!!
