I was the recipient of hundreds of leftover film canisters from a local photo organization and wanted to make a relatively easy, low-cost project that I could do with students. This version requires no soldering, but hopefully someone will take this idea to the next step and add arduino capability. These little lanterns are safer and last longer than candles. Shades are interchangeable to match theme or mood.
One bright or ultra bright white LED
One coin cell battery, 3V
Transparent film canister with cap
Toilet paper tube
Needle nose pliers
Glue or double sided tape
Step 1: Homemade battery holder
Cut 2 cardboard tabs, 1/2"x1" each. I used a toilet paper tube, since this is needed in a later step. On one end of each tab, cut off corners and bend.
Use a glue gun to glue tabs, bent side out, into canister cap.
Step 2: Light fixture
With needle nose pliers, bend the positive (longer) end of lead into a hook. Bend the negative end into a smaller hook in the opposite direction. Use electrical tape to secure the positive lead to the positive side of a coin cell battery. Test.
Place battery and light into holder, and tape positive side to cardboard tab. Adjust so that the light turns on when the negative side tab is pressed and turns off when it is not.
Step 3: Adding a 'switch'
With a nail, make a small hole about 1/2 inch up from open end of canister. Cut a toothpick into a 3/4 inch length and insert into hole. Slide to check that the toothpick will move smoothly back and forth.
Carefully place canister onto cap so that the hole is across from the 'negative' side. Insert toothpick and push in until lantern lights up. Pull out slightly so that it turns off. Adjust as needed.