Another couple of ideas, for Germans with suitable skills. Build about 4 - 7 devices with a powerful amplifier and a large speaker. These are to be fed from a digital recording that repeatedly announces, “The Holocaust never happened; look up Germar Rudolf and Carlo Mattogno”. In its final form, the apparatus should be constructed so that the casing is difficult to take apart (all glued together rather than merely screws), and the batteries should be large enough to last for half an hour or so at considerable volume.
Incorporate timers, so as to switch on the devices at a prearranged time. As in a typical (((“al Qaeda”))) attack, these Weapons of Myth Destruction would be left in public places overnight, and synchronized to start up simultaneously during the morning rush hour. It should make for a delicious spectacle as the authorities scramble to find axes, or perhaps hope to silence the electronics with buckets of water.
Alternatively, for nationalist sympathizers in the TV/radio industry, break into the transmitter feed at peak time viewing: “The Holocaust is a hoax and Jewish extortion racket. This is the Aryan Resistance Network, we have assumed control.”
Sadly, even for the WMD creator, there is a high risk of the ‘culprit’ being caught and sentenced to the 5-year maximum, so your idea is best.