Chuck has been making finders out of found materials for years. By far his most popular design (so far!) has been his classic 35mm film can finder. Here's what Chuck says about it:
Basically, I used a 35mm film can and glued a lens (you might find something at Surplus shed on the net) with a focal length of about 2 inches to it (which is the height of the can). I used a small block of wood, drilled a hole through it the size of the outer diameter of rubber hose that had the inner diameter of an LED. Cut a hole in the lid and nailed it to the block, lining the holes up.
Scratch a dot, arrow, or whatever you want as a reticule on some black exposed slide film with a sharpened pin, (need to make it small!).
Cut that out to the size of the tubing, glue it to the end of a small piece of the tubing and stick the LED in the other end. This assembly then slides into the hole, and can be slid in and out to focus. If you don't have the finder focused properly, your reticule will wander in the sky.
I used two button batteries. You can use 3 volt lithium also. (If you use AAA's or AA's you have to use a dropping resistor. There's not enough internal resistance in them, they'll smoke the LED.)
Just wire up a switch and potentiometer (10k works good, I used the sub-minis,) and you are good to go. The window is just a thin piece of Plexiglas glued to an upright with a hole drilled in it and attached to the film canister. When you get your tension right, you can change the angle for up and down and rotate the canister in the lid for left/right adjustments.
I sent some info and pictures to a forum on some other approaches; see
the following: http://sky.maplevalleywa.com/cgi-bin/MVASBoards/YaBB.pl?board=Equipment;action=display;num=1129093434
and go to "discussion boards" then "equipment" then
Here's a couple of pictures that might explain it better:
The battery holder is the corner of the block cut out
with a table saw, with brass sheeting cut to size and backed with foam tape.
You have to experiment on a test piece to get the distance right.
Holes are drilled from the bottom of holes to the battery holder, etc
Here's the circuit for the LED.
If you have further questions, Chuck can be reached at the email address to the left. (This is a graphic file to thwart spambots, so you'll have to copy it by hand.)
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