If you like to decorate for your units, this is a great time of year (Fall) to pick up the Gemmy Lightshow Lights.
Our local Lowes and Big Lots stores both have them. We use the blue ones to create water effects and the red ones to create flame effects. The one pictured on the right is called a "Gemmy Fire and Ice Red & Yellow LED Lightshow Projector". The stake screws into the handle. When we use them on the floor, we stack 3 bricks with holes and feed the stake through the hole for stability.
Below is a picture of our "furnace" figures that we created with plastic tablecloths and cellophane for our Daniel and his Three Friends Unit using the Gemmy Lightshow Lights (copied from "What's in Your Supply Closet" here at rotation.org.)