cr0sh:
If you do this, don't fill it with hydrogen in this manner.
I agree. Although we used to fill 75 liter garbage bags using a slightly different (but just as dangerous) reaction. Everything was weighed accurately and cold water baths used to control the reaction rate. But I studied chemistry so was aware of the dangers, and what was the quickest way to the shower, and to the hospital. Still a silly thing to do.
BTW, hydrogen will ignite over a huge range of O2 concentrations. Even a few percent of oxygen could likely turn your blimp into a bomb.