LOX and LOH tanks are usually high grade stainless or nickel based alloys. High temp resistance as well as structural stability at low temps. That being said don’t crack them open.. Blobs, Green Slime, or decepticons oh my.
Yes, but most of the time LOX and LH2 are low-pressure, thin walled structures. The fuel and oxidizer are pressurized using turbopumps. The External Tank of the Shuttle was thin-walled and collapsed on itself during re-entry, leaving a debris field in the Atlantic.
Now, if there are no turbopumps involved, then you would need a much thicker tank, as the fuel and oxidizer would be under high pressure.