In experimenting with making my own batteries from lemon juice, I became intrigued by the design mentioned here:
https://www.instructables.com/id/The-micro-Lemon-Battery-reusable-1-hour-of-led-l/step16/Other-designs8-The-CPA-lemon-battery/

The design uses dish soap, copper foil, and aluminum foil. I readily had these items on hand, so I created several designs to eventually settle on the one described here.

In this instructable, I use 2 pennies, a paper towel, three strips of foil, and duct tape to create a relatively clean package.

I am trying various joule thief designs with this battery, but don't think it can source enough current for the inductor to generate the 3 volts required for LEDs.

Step 1: Gather Ingredients

To build a 1V cell from pennies and foil, you will need:

Duct tape
3 Strips of Aluminum Foil (Fold it over 2 or 3 times to make sturdy strips the width of a penny)
2 Pennies from 1981 or before (these 95% copper, vs a thin coating)
1 Paper Towel
Dish Soap
Scissors

More about copper content of pennies:
http://coins.about.com/od/uscoins/f/copper_to_zinc.htm

Step 2: Build the First Layer

Moisten some squares of paper towel with dish soap. The squares should be larger than the penny, but smaller than the width of the duct tape.

This battery is 2 layers wired in series. This means we will have 2 distinct layers separated by duct tape.

First Layer:

To begin, lay duct tape on the table and place the negative lead (made of foil) directly on the tape. Let it stick out towards you.

Now add dish soap moistened towel, penny, and a strip of foil sticking out opposite the negative lead to connect the two layers.

Seal the first layer with tape and fold the foil over to form the base of the second layer.

Step 3: Build the Second Layer

Second Layer:

Building on the foil from the sealed first layer, add a dish sop moistened towel square. Now add another penny

Add a final strip of foil to act as your positive lead. This should face you like the negative lead.

Seal the second layer with tape and fold the foil over to make the positive lead lay flat against the tape.

Step 4: Measure Your Voltage

Use a multimeter to measure your voltage. You'll need 2 or 3 volts to power most LEDs; you can wire two or three of these in series to drive LEDs.

I am trying various joule thief designs with this battery, but don't think it can source enough current for the inductor to generate the 3 volts required for LEDs.