kalium permanganate was put on the list of substances that can be used for narcotics preparation
I'm not sure where you are located or how thorough the local authorities are, but it is possible that you will find potassium permanganate in a pet shop; it is (or was) used as a fungicide for tropical fish. Where I am, oxidizers such as potassium nitrate are unobtainable through local retail channels, unless you know to look for "stump remover", which is mostly KNO3....
you can also get saltpeter from a pharmacy
it cost about 3 or 4 dollars
I posted the circuit diagram for a bulb flash trigger circuit in the third post in this thread. It uses a capacitor and a resistor too. If my memory is correct, the standard battery for these was 22.5 volts and was similar in size to a modern 9 volt battery but had a contact at each end.
Yes, I saw that. It may very well be 22.5 volts but the unit I took apart didn't have any discrete components. It was just wired in serial fashion.
Here in the archives, AKA Junk Collection, is a Honeywell Tilt-a-Mite which used a 15 volt battery. It was a very compact unit with a capacitor plugged in next to the battery (suggesting they expected some life expectancy trouble). I think I bought this in the early to mid 1960s.
Since the combustion products of aluminum in air are solids (oxide and nitride) at first glance it seems that there would only the the 1% or so of inert gases to create pressure from the heat of the reaction. In practice, there is likely to be excess air plus miscellaneous contaminants, and the solids don't form until the reaction products cool, so, yes, a flashbulb is a small bomb of sorts. The thick plastic covering of commercial bulbs is there for a reason.
You might reconsider if you examined the burning rate of flashpowder as a function of pressure. A small pile lit from the top burns with a vigorous "foof" but the same pile lit from the bottom is a lot more exciting. The weight of the unburned chemicals serves to confine the reaction, with the result that an explosion of some size results. (Black powder, as used in firearms, behaves the same way.) In large enough quantity, this effect can lead to a high-order detonation, without the benefit of a blasting cap or any other detonator. This can create small high speed particles out of things that aren't even brittle (metal, plastic, your hand, whatever).
The "explosion" of a flashbulb isn't that dramatic, in my recollection. As a kid, I used some uncoated flashbulbs (this would have been in the 1950s; maybe they predated the era of plastic coating) and the "pop" would by a rustling sound as the fragments fell. The glass was so thin that the particles were individually pretty light, and lost velocity rapidly due to air drag. However--GE, Ansco and the others knew what they were doing, and I'm not sure a home-brew version would necessarily be as benign.
I do remember reading something by somebody who did a tour of a flashbulb factory and saw workers using pencils with a rubber tip to push the metal wool into the bulbs. I'm pretty sure they said they were using aluminium. Could have been magnesium (?)
Sylvania came out with bulbs containing zirconium which would oxidise faster and burn brighter.