The basic idea is to have multiple concrete cubes making light from one side and having power on the bottom and on the top. this way you can stack multiple lamps given the correct voltage and amps every time you add a lamp.
Step 1: The Wood Stamp
The wooden enclosure to make the concrete dry in and have the shape.
leave at least 2,5 cm each side for the walls.
dont go over the center.
Step 2: The Electricity Bar
very simple design a smaller bar in a larger tube.
a hole at 3/4 of the tube to make the wire pass in to it, solder the 2 wires and
wrap the inner rod with plastic tape, so the electricity cant flow from the tube to the rod.
Step 3: Positioning
Position the tube in the center of the wooden structure base.
put the wires in the hole as in the photo
Step 4: Plastic Wrap and Cement!!
wrap the inside of the wooden structure with alimentar plastic, to avoid braking when you exctract the wood from the cement.
Put the cement in the box!
Step 5: Enjoy Your Lamp!
of course you have to solder the led before that :)
If you repeat the process you can stack as many lamp you want as long as you make the right calculations with the voltage.