I've been asked about the windows and doors a lot. It is not that difficult, actually, almost no different than a traditional steel building (like what most sheds and garages are now made of). Just requires an angle grinder with a cutting wheel or an electric shear (~$50USD for either tool). From there you can use the same flashing/trim as a steel building or get creative with some old barn wood or other recycled materials. No welder required. As far as handling a tornado, I could see if you set the bin correctly, that it could possibly be safer in heavy winds than a traditional square building. Then again, I have seen solid brick buildings toppled from a tornado, so I guess it is all a big, "it depends". Probably, the best bet there would be to build forms for a small crawlspace/storm shelter before pouring the concrete pad.