I own a 3 kW electric heater (Grafner eh10934) which I use as an engine preheater. This reducing adapter connects the heater to a heating hose which is then hooked up to the recipient. The reducer attaches to the heater using a bayonet type connection and grabs onto the existing screwheads of the heater. You can attach or detach the reducer by simply twisting it on / off. The hose is connected with a standard hose clamp.

Caution: These electric heaters go up to 85°C so you must use a heat resistant filament such as ABS, ASA, PC or PETG. You cannot use PLA because it will melt at 60°C.