I made this by loosely following the pictures on this website http://www.ragarecords.com/photo/diy_viewfinder.html

Got the Kodak camera for $4 at Target, it may be possible to get them for free but my local drug store seemed to think that I was a bit crazy for asking. Threw away the film, got the one piece plastic viewfinder assembly out and ground the plastic down until it fit with a Dremel type tool.  Don't get shocked, discharge the capacitor and don't do this if you don't know what you are doing.

An improvement that is suggested after trying it is that; the lens does not have to go all the way into the flash socket, it is actually better if it sticks out the back about half way so that you can get your eye up close to the "viewfinder". I may make a second one if I can get some free cameras.

The angle is about 35mm if you can get your eye right up to it, which should work  very well with the 17mm or use the 18mm setting on the zoom lens. You can simulate telephoto by holding the camera a few inches away.

I don't know if I will actually use it, but I'm going to try it and see.

How do you know if it really is the right focal length though?

You mean, how do I know that the viewfinder is 35mm? Because it matches the view that the camera sees when I set the zoom to 18mm (36mm equiv. ). Yes, it only has one focal length, so it might be a lot more useful for the pancake lens that is 17mm; it is about the same view as the Oly viewfinder.  Still, it is something to look through, and you can guess the coverage of the zoom pretty well. I think that I prefer the LCD though, I just wanted to try this.

Here is what is looks like, sort of, kind of hard to reproduce the effect with a camera.

Hey, thanks for sharing!  I don't know how practical it is, but it looks like a fun thing to try.