The Kume Shade

NoTech Magazine describes a DIY window shade that provides not only good insulation, but probably would work very well as a blackout curtain. From the article:

The Kume is a roll-up curtain that is composed of four distinct layers.

• A front panel which acts as the first layer and seals the perimeter of the window opening when the curtain is closed
• A moisture barrier which prevents indoor humidity from reaching the window and condensing on the cold glass and window frame
• Wooden battens which maintain the fabric stretched out and thereby ensure that the curtain fits tightly against both sides of the window opening (the battens also create air pockets which further reduce heat losses through the curtain)
• A back panel which acts as the final layer of insulation and helps seal the perimeter of the window opening when the curtain is closed.

Instructions and further information for building the shade can be found at the Kume Project.