Inspired by https://www.thingiverse.com/thing:3017248, and https://www.thingiverse.com/thing:2207534 (but technically not a remix, I modeled everything myself).
I bought a Mosquito Magnum hotend at MRRF2019, and I had serious problems getting it up to temperature (even at just 205 celsius), whenever my cooling fans were on. The fans were not pointed at the hot end, but the reflected air from the bed was enough to prevent it from hitting temp. I tried buying their 50 watt heater (and verified it was pulling 50 watts), still no dice.
I have been using a sock on my E3D V6, so I figured I would try making one for the mosquito, which led me to https://www.thingiverse.com/thing:3017248. Unfortunately I had a fair bit of trouble getting that mold form to work, the walls were very thin and it kept tearing. I started working on my own form, inspired by https://www.thingiverse.com/thing:2207534.
I used this silicone:
Permatex 81878 Ultra Copper Maximum Temperature RTV Silicone Gasket Maker, 3 oz. Tube
One 3 oz tube could probably make 6 socks. You should be able to buy this at your local auto parts store.
I followed the same steps in this video: https://www.youtube.com/watch?v=GtZfnc6XLjM . Got a bowl of SOAPY water, dunk your hands in it, squeeze a good bit of silicone into the water, then massaged the silicone in it a bit, dunk the forms in the same soapy water, then filled the form up about half way with silicone, then inserted the hotend/lid/handle. The excess oozed out of the holes in the lid (which was their purpose). about 24 hours later, It fairly easily slid out of the box, and off the hotend form. A bit of cleanup later, and I have a pretty nice looking sock. I had to make a small cut on the sock on the side my heater/thermistor wires come out, then it just slipped onto the hotend with a small bit of finagling to get everything settled.
Once it was one, I turned my cooling fan on 50% (what I normally run them at), and set my hotend to 205. Less than 2 minutes later, it was up to temperature, and held the temperature through several 2 hour prints without problem.
I also tested with the fans at 100%, and 240 degrees, and it had no problems getting and staying at temp.
The "box" part has a brim on it with screw holes, because I wasn't sure how much force would be need to unbox the cured sock. Turns out, it required very little.