This is a pattern for making a jacket to fit around the heater block of an E3D. Its made from fibreglass heat shielding - the kind used in cars to cover exhausts. I use the same material under the bed to keep the heat in.
DO NOT TRY THIS AT HOME, but, at 200 oC you can touch the outside for a few seconds without getting burned.

Take a suitable piece of fibreglass heat shield, cut slot and holes. cover edges with Kepton tape to stop fraying. Remember to fold silver side in. Secure with another piece of Kepton across the two flaps