This is a split hydrogen/oxygen generator, which means that instead of hydrogen and oxygen coming out of the same place in the typical HHO generators (which creates explosive mixtures that aren't really useful or safe) hydrogen comes out one side while oxygen comes out the other. This is good for testing, such as a simple hydrogen candle or for fuel cells which require pure hydrogen. It also allows for safer experimenting, rather than the dangerous HHO gas.

Assembly:

To assemble the split hydrogen cell, print two identical models labeled “Main Box” and one model labeled “Membrane.”  Place one of the “Main box” models and insert a metal electrode. The metal electrode i used is a thin piece of stainless steel. You can also use other metals that don't corrode like nickel.

Cut it in a way, so it's a square with a long rod out of the corner like this: 

Put it into the main box, making sure to slide the long rod into the cut of the main box. After that put the “Membrane” model onto the main box making sure to cover it entirely. IMPORTANT: Make sure to put a small piece of nylon or felt onto the hole in the membrane. This is what makes sure the cell makes split hydrogen and oxygen!!!!!!!!!!. I used nylon from a kite and it works well. 

After that put the second main box piece with the second electrode onto the membrane making sure the open part of it faces the membrane, forming a sandwich. Glue everything well, making sure there are no leaks of air after blowing through one end and closing the other.

How to use:

Attach two 4mm hoses onto both of the ends. Make a solution of water and baking soda. You can also use sodium hydroxide, but its much more dangerous. After making a solution, dip one hose into the solution and suck the solution into the generator through the other hose. After it's filled, apply a voltage of NO MORE THAN 5V! by connecting the + and - to the metal electrodes. After that hydrogen will come out of one hose(cathode) and oxygen through the other(anode).If you have any questions don't hesitate to ask!!!