A short read, schematics are easy and accessible in terms of assembly instruction and required materials (most devices require little more than paper, foil and adhesive), the author vehemently mentions his patents every so often and it’s kind of funny which only added to the experience, I’ve constructed the occult illuminator and while I have yet to see visions of beasts, humanoid forms and strange eyes, it makes for an interesting optical illusion and I found it useful for meditation, provides enough stimuli to keep the mind from wandering but not distractingly so.