Interesting things going on in my few days absence - I got bored so set up my own darkroom, now poor but happy.

My advice? Don't do it. Or if you must, and sometimes the need to explore make this the case, then research every aspect of the project to the greatest depth. Then think about how to make it safer - not just the final product but the manufacturing process too. Every detail must be understood - how will the glass react to the thermal shock? How will the lacquer react to high pressure, sharp objects, oxygen, heat and flame? How much heat and flame? For how long? And we haven't looked at the chemistry yet....

There may also be legal issues depending on where you are and your reasons for doing it.

Stay safe.