Glowing mushroom for your desktop that is powered by any colored LED and batteries(or usb).
The legend says that:

• Green mushrooms are magical
• Blue mushrooms are ghostly
• Red mushrooms are poisonous / viking fuel ( http://en.wikipedia.org/wiki/Amanita_muscaria )
  Designed to be printed with PLA and to fit 2x 2032 lithium 3v batteries, a switch, led and a resistor. The leg of the mushroom is hollowed (3mm) for the wires and the resistor.
  Batteries are neatly hidden under the base. Switch is behind the base.
  Works ok as a ornament when printed with nontransparent plastic.
  (as a side idea the glow was to be produced with a UV led and with a glow in the dark plastic..could still work)

• Print all the parts (unsupported or supported->leg.stl)
• Clean well (the lid and its tracks are hard but they\\'ll work)
• Do all the top solderings (led+resistor*+wires)
• Cut the led and resistor legs short(5mm from top..or so)
• Solder the black wire to the cathode (shorter leg)
• Solder the anode (longer leg +) to the shortened resistor and the wire
• Insert the top assembly correctly from the top (wires first)
• Cut and run the wire from the side to the switch** and solder
• Glue the switch in place (legs and all)
• Strip the wire from switch bare, solder and turn it in to a coil for a contactor.
• Cut black wire approx. 20mm from the hole and strip. Solder and turn it to a contactor.
  *resistor formula..
  power voltage(V) - led voltage(V)
  ------------------------------------ = Resistor (Ohm)
  amps used by led (A) (usually 0.02A)
  **switch
  The switch used is made from circuit board multi switch by sawing. (just cut one of them free with hack saw.) be careful with the legs, they are fragile, I wasted mine cos I did not glue it well enough...