Hi, I've looked everywhere for some advice on this, I hope someone can help. We are making a cooling system for cooling thin films, and part of that setup is a liquid nitrogen-cooled cold finger. This cold finger will be inside an aluminum tube, and will move closer and farther away from the thin film, which is mounted on the tube. We could buy a cold finger, but they are all Pyrex or glass, which could scratch, and they mostly have inconvenient shapes. If we could make our own out of aluminum (because it needs to be nonmagnetic and conduct heat), that should work great. Does anybody have design ideas for making this? The basic idea is just to circulate the liquid nitrogen in and out of the cold finger, but we're not sure how to seal the aluminum and have the in/out tubes fit properly. Thanks!