This design is based on the great work of vietquocnguyen.
I just tuned the design so that the sock itself also generates additional insulation in between the heater cartridge and thermistor wiring (shorting those line via the hotend will fry your mainboard).
The base design is a “just slip on” design which can be just slipped on the hotend without disassembling anything.
It also features the possibility for the thermistor to be pressed into place with the sock between the screw and the thermistor. This may require partial disassembly of the hotend.
If you are anyway planning to disassemble the hotend you might also consider my very own design https://www.thingiverse.com/thing:3633287 which creates a thicker sock for maximal insulation and easier casting (less air bubble while casting). This design can not be pushed on the hotend without disassembly.
The Clamp is an optional part which seals the bottom of the mold
Use anti adhesive spray for the mold before casting the silicon. I reached good results with baking spray like PAM.
For casting I am using "TFC Dubliersilikon S-ROT mittelhart Shore 33 1 1 HB", but you should be fine with any temperature resistant silicone like e.g. Mold Max™ 60 Silicone.
You will need about 10-15ml as shown in the picture.
I am also using a ultrasonic cleaning bath to shake the air bubbles to the top. Others just attach a ultrasonic toothbrush with some tape to the mold to shake it.
does not matter
cutting silicone sock
use a scalpel and a sharp clipper to cut off excess silicone as shown on the pictures.