heat pro repman heater for preventing warping.

Using 3 pieces of acrylic, 1 6inch by 6 inch board and 25 to 30 220ohm resistors i made this heater plate. you can make it too! -

i soldered one end of the resistors to the copper board, applied a thin layer of tape to the area across that was not soldered, and then soldered the other end to a wire . the red wire was positive, the copper plate was negative, i then soldered the copper board with a black wire, and then taped several times over the copper side with the resistors several times