I am a recycling geek. So just added a simple bulb from a old torchlight and a plastic bottle. The switch is made from copper tape, so when I make contact from bottle top (funnel) to bottom then buld lights up.
Step 1: Materials Needed
You need 1 plastic bottle any size. 2x1.5V batteries and a battery holder for it. About 20 mm copper tape sold at hobby shops. Some thick foamy doulbe sided type. 1x2.2V bulb salvaged from a old torchlight. 1x bulb holder(can be screw in or twist in depending on bulb type). About 50-100mm insulated wire depending on bottle size. Soldering Iron and solder.
Step 2: Step 1
Cut a soda plastic bottle using a cutter about 1/4 way from cap. Cut all around. Later can use scissors to trim any uneven edges.
Step 3: Bottle Cut
This is how the top half and bottom half contact to on the light something like a touch switch.
Step 4: Making the Bulb Hole
Using an old soldering iron, I made a hole on the cap at the centre about the side of bulb and pushed bulb in.
Step 5: Battery
Attach battery to the bottom half
Step 6: Joining Up the Contact Switch
Now solder some wires to the 2 end of bulb. The two free ends should each be soldered to a copper tape pasted at the edge of the bottom half of bottle. This forms a closed loop (see photos)
Step 7: Completed Torch
Photo shows completed bottle torch. Now all you need to do is wrap a rubber band over wires on top half so it sits nicely into the bottom half. Once the two halves copper tape comes in contact the torch is activated.