I used an old wooden box lined with plastic for the base. The fairy house is actually an unfinished wooden bird house you can purchase at craft stores. I altered it with moss, sticks, and such and made a dwelling fit for a fairy!
A nice little path of colored gravel leads right to the hinge front door. The door knob is a teensy snail shell that was found in the moss.
Here is a view from another angle. You can see the fun gold ball that I added. I've been collecting interesting objects to add. The blue stone by the door is a piece of glaze from a clay pot. There is also some wee pine cones, interesting sticks, an old pop tab, and a piece of broken mirror, nestled amongst the moss.
Plans are in the works for a smaller version of this too. See kids, work can be fun!