A short overview video:

I needed to make 15 simple circuits with a light, battery and switch that could be easily assembled and disassembled multiple times for a Cub Scout camp activity. The light need to be bright enough to be visible in direct sunlight (working outside). And they needed to be as cheap as possible.

The prices, parts and sources were the cheapest I found for ordering enough for 16. I ordered 1 extra because it was cheaper then needing to order a replacement later if a piece was lost or failed due to shipping costs. The batteries are the only thing that didn’t come as individuals, but ordering significantly more or less of these may result in another source being cheaper.

16x RL5-BR2020: Super Bright (4000 mcd) 5mm Blinking Red LED - $ 0.54 ea - $11.85
16x SPST10: SPST on-off Miniature Toggle Switch - $0.60 ea - $13.60
2x Lithium 3V Batteries Size CR2032 (Pack of 25) - $3.95 ea - $7.41
10ft Solid copper 18 gauge door bell wire (two wires) - $0.23 ft - $2.53
Electrical tape (on hand)
Solder (on hand)
Hot glue (on hand)
Scrap wood (on hand)

Total price: $35.39 (with shipping, tax, etc.) or $2.35 each (with one set of spare parts)

Some of the pictures are upside down. They appear the correct orientation on my Mac as it reads the orientation information from the camera but provides no convenient way to rotate images like Windows 7. Sorry about that. 

And here is one circuit blinking:

Step 1: The Boards

The wood I used was 3/4 inch thick. I had some that was only 1/2, but it was a little thin, so I recommend the 3/4 inch. I cut it into squares with 3 to 4 inches per side. The thickness of the wood is dependent on the size of the switch. 

The more C clamps you have the more boards you can work on at the same time.

Each board has a large hole for the switch. This hole is made with two different bits. First drill a 1/4" hole clear through, then a 5/8" hole most of the way through. Use masking tape on the drill bit so you know when to stop. Leave just enough wood to hold the switch in place when you tighten the nut.  

I then drilled 6 small holes in the wood. The holes right next to the switch mounting are used to run wires from the poles of the switches on the underside to the top of the board. The other two sets of holes are for the battery and LED respectively. You want the holes for the switch quite close to the 5/8" hole. The other two holes should be about an inch appart. You might make a battery assembly first and examine the leads on your LEDs first to see what is the idea distance for those holes.

Experiment with bit sizes to find one that works for the size of wire you are using. The holes should be just barely larger than the wire that goes through them. The idea is that by poking two wires in the same hole it should be tight enough to maintain contact between the two. I forget what size bit I ended up using. I think it was the smallest I had.
awesome. I was looking for something for a similar situation- a quick experiment with a simple circuit that would be easy to understand, but cheap enough to do with groups. thanks for posting!
Jim McKeeth - what's new, bud? Nice project. LED projects are fun.<br><br>Scott Cooper
Oh hey Scott. Good to hear from you. I thought I would try my hand at posting an Instructable. It was a fun project. Drop me a line some time.

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Bio: Father who enjoys tinkering.
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