I apologize for disagreeing with all the experts out there, but a glass
thermos works just fine for holding liquid nitrogen. I pre-cool mine with
a small amount of liquid first. I did a side-by-side comparison at one time.
The glass themos retained more LN2 (about 20%) than a steel themos over the
course of 24 hours. Both worked well. I use one or the other, depending
upon my need for safety (sturdiness) or efficiency. I have transported both
in a car, set in styrofoam boxes to keep them upright.