hydrogen cell tb - Version 1 Completely free toolbar from www.hydrogencelltoday.com - Is it possible to build a hydrogen fuel cell yourself? Yes, of course it is, it's not that difficult to do and for less than $50 you can build a fuel cell that will increase your mileage by as much as 65% or more and that's not bad.The first thing to know is that the device that you built for your car is not meant to produce enough hydrogen to run your car only on hydrogen. To run 100% hydrogen means you have to build a device which is much more difficult to put together and probably more dangerous because at least at the DIY level the technology isn't there yet.The unit that you're going to build works this way. Quite simply, you will be generating HHO gas from water by sending a charge from your battery into the fuel cell which separates the water molecules in the fuel cell into hydrogen and oxygen. This then generates a gas known as HHO or Brown's gas.