@MegaMantra - thanks; "tour de force" is probably the nicest thing anyone's ever said about a thing I've done... and it's cool that I have a sound.
@Idio - glad you think so. I worked hard on them but in many ways the odds were against me - I can't draw, they're floppy disks, etc - so it's good to hear they're cool. I sent out the first round of them today, so I hope yours gets to you okay.
Incidentally I've unfortunately had to raise the shipping costs... nothing preposterous, but it turns out the USPS will not in fact ship a padded mailer as a large envelope, which makes a big difference when sending overseas. Sorry everyone.