I've been researching microfilm mani mantras, even though (as remarked previously) I am not entirely convinced they are the way to go. Nevertheless, one wishes to keep an open mind.
The rolls (known as "pancakes" in the trade) are 2000 feet, and contain 616,896,000 mantras. The pancakes have three inch center cores, and are nine inches in diameter. Weight is approximately ten pounds. The medium is 16mm film, so the rolls are roughly 5/8" thick. Cost is USD $80.00 per roll, plus a USD $20.00 handling fee if one orders less than ten rolls. Shipping is extra.
So -- for the sake of argument -- twenty rolls are USD $1,600., plus shipping, and for this you get 12 billion 337 million 920 thousand mantras. According to the Central Intelligence Agency, the estimated total human population of the earth (as of July 2008) is 6 billion 706 million 993 thousand 152 (am I glad somebody is keeping score). Everytime this baby spins, you will release a mantra for every man, woman, and child on the planet, as well as about 6 billion other sentient beings.
For those of us who imagine that USD $1,600 is too much, there are alternatives, but this is one project where you want to go large.
Say you want to put USD $6,000 into this: $1,000 for each of the six syllables. A nice three foot wheel, nine or ten inches in diameter, is going to be more than enough to spin 37 billion, 13 million, 760 thousand mantras: $4,800 for the microfilm and $1,200 for the wheel.