Cheap strong neutral density filter hack for long exposures

You know those terrific landscape pictures where the lake looks like a sheet of glass?  Or a waterfall is all milky smooth?  Or the clouds streak in haunting wisps?

Well, you know as well as I that that is accomplished with long exposures (and a steady tripod).  But in order to take said long exposure without completely blowing out your scene, you need to either shoot around abouts daybreak or sundown.   If you are anything like me, you don't really want to get out there at dawn.  And even at sunset, the light changes fast and you may have to change your settings frequently.

Another option is to use a strong neutral density filter to reduce the light input and allow shooting in brighter situations.  The really good ones (and the really dark ones) start to get expensive.  So, if you are like me and always looking for a bargain, or just like the DIY take on things, you may like this alternative.

A Lincoln Electric #10 Shade Welding Lens Replacement.  $5 at Lowe's.  Until you hold it up to a good strong light you'll think it's black through and through.  Nope.  It's transparent, but just barely.

This terrific shot by CJ Schmit: http://www.flickr.com/photos/cjschmit/5640554874/in/pool-1182517@N23/
was shot using this very same welding lens.

So I just bought mine and I can't wait until conditions are right in my area for me to try this out.  Just have to think on how I'm going to strap in onto my wide-angle lens (probably great big rubber bands, maybe binder clips, too)  This may also involve some sort of rubber gasket. I'll post my results when I have some to show.

Hope this tip is useful to you!