Hi everyone,

I've been playing around with a kit of mine trying to finish it for pics, but the results of one of my items were so good I decided to post it a bit early.

Some of you might be aware on the periphery that the hard drive disk in your computer is likely either glass or aluminum with a magnetic coating. These platters spin at outrageous speeds and can not deform in any meaningful way. Thus they are very resilient, flat, and almost perfectly reflective because of this.

I had a stack of old Jaz disks (Iomega) laying around and realized that they might make a good signal mirror. You can pick up a Jaz disk on eBay for pretty cheap - it really doesn't matter what shape it's in unless it's had a head crash which may scratch the surface. Each Jaz disk has 2 platters, and you can get them as cheap as a buck. One could use an old 3.5" or 2.5" hard drive in much the same manner.

The disk platter works as a great signal mirror. I tested it side by side against a similarly sized Ultimate Survival 2"x3" mirror.


The Jaz signal was much brighter and less "spread out" by the time it hit the target (my porch siding - the Jaz is on the left) 10-12m away.


Keep in mind that the siding is dark gray and absorbs a lot of the light. Reflected against a shiny or white surface, it's actually difficult to look at. It can light up a car's reflectors from a block away without ANY difficulty in broad daylight. I find it to be at least twice as bright as the US 2x3" and I've carried it in my pocket with other metallic objects without much damage. It does not scratch easily, however I would recommend you get a "badge holder" available in any super-mart or office store. The thin pieces of clear plastic make a decent carry and protector for the mirror and they allow it to "signal" even if you are unconscious.


Cost of Jaz disk - $1-2 if you can pick it up locally (no shipping). Cost of protectors: $1.50 for a pack of 20 Wal-Mart specials. Super flat, very thin, and highly portable.

hmm... i got a very similair purpose made "signal mirror" that looks like that. But mine is made of paper with a shiny reflective side. Not the greatest performence, but nice as a backup mirror.

This is solid Aluminum with a nicely rounded over edge... could probably be sharpened for minor cutting duties, but I like it like this for easy handling. It's very stiff and sturdy not to mention light.

Neat idea. I have two defunct WD drives out in the computer graveyard in the garage. Time to see if they'll perform better in this new role!

p.s. - that platter looks to be about the right size to fit inside a screw-on Nalgene bottle lid. Since that's my pack-based survival kit I'll have to give it a shot. If it doesn't fit there, it will surely fit pressed up against the bottom of the bottle, nested within the little metal cup specifically made to fit the end of the bottle. That little metal cup is pretty shiny in its own right.

I have a knock-off bottle, and I don't think the top is the same size as a Nalgene (mine didn't fit like you suggested). It has a diameter of 6.5mm with an area of 30 sq. mm once you subtract the 2mm center. In comparison, the 2"x3" Ultimate Survival mirror is 7x4.5mm with an area of 28.5 sq. mm once you subtract the targeting circle and the corner lanyard notch.

"I don't think the top is the same size as a Nalgene (mine didn't fit like you suggested). It has a diameter of 6.5mm"

Well, that's gotta be just the cutest little bottle on the planet. You'd have to be careful sipping water from one though ... quite the choking hazard I'd think. <img src="/images/graemlins/grin.gif" alt="" />

I'm very careful when I sip. <img src="/images/graemlins/wink.gif" alt="" /> Sorry, I mean those stats as cm. No idea why I put mm.

These are great signal mirrors. I just stopped by the student-run U of I computer store to see if they had any available. They gave me one.....free. Are these like zip drive discs?

Kinda not really. These are IIRC a magneto-optical drive. Zips were pure magnetic, just over grown floppies and just as sloppy.