First we need a rectangle aluminium pipe. 

Then we need a acrylic sheet. That will cover the whole aluminium rectangle pipe only leaving the area of peltier which will touch the aluminium and will keep the peltier in a room temperature. 

From back side of the light we also will cover it with acrylic sheet. From this we will make a whole like a (i) for air circulation. That will keep the aluminium and peltier inner side at room temperature. 

 These are the some pictures those will help how the flashlight is made. About LED strawhate 8mm 0.28W will work. In my own experience 1W special LED work very well. If you find this ok otherwise do not use 1W it does not use it. You can 8mm strawhat white LED 0.28W. More about LED selection few other things you can find in instructions