A mold to make your own silicone rubber sock for the E3D V6/Lite6 heater block. Insulating the heater block keeps the nozzle temperature stable, unaffected by the part cooling fan and other external temperature changes. Print with 1 wall. Left and right side version included with cutout to allow exit of thermistor / heater cartridge wiring. Prepare the mold by lining the inside with scotch tape (silicone rubber won't stick to scotch tape). Cut out tape covering the hole for the nozzle and heater cartridge wiring window. Prepare the heater block. Wrap the heater block with teflon tape (used by plumbers, silicone rubber also won't stick to teflon). Make sure to cover the nozzle as well. Press the teflon on the area around the nozzle to shape it more or less like the nozzle itself. Fill mold about 2/3 full with high-temperature RTV silicone rubber. Make sure the corners are filled properly. High-temp RTV silicone rubber is available in auto-parts shops and they come in tubes. Buy the highest temperature rating you can get. Push the block into the mold until the nozzle cone goes through the hole and nozzle nut hits the bottom of the mold. Make sure the nozzle tip comes out of the hole at the bottom of the mold. Excess silicone rubber will go up the top side of the heater block. Use an oiled spatula to shape the excess silicone rubber on to the top of the block. Let dry for at least 12 hours before removing the mold. You may have to break it open if it gets stuck. Let cure for 24 hours before using. Make sure to remove teflon tape covering the nozzle tip before using. Recalibrate PID settings. Cured siliicone rubber sock can be removed from heater block if necessary.