One of every 6500 Hydrogens is deuterium, that is a hydrogen atom with 1 neutron, 1 proton. So deuterium is very rare, but you can most definetely "make it".
You don't actually make it because its already made, but you can separate the deuterium from the regular hydrogen, once process is by water electrolysis.
You get say 10 gallons of water, you make electrolysis until you have say 1 liter left, because deuterium is heavier (my speculation) you end up with all the heavy water in the 1 liter, you do it again, again you have all the heavy water, again, again, again, again, and at one point you will start to actually hydrolize the heavy water rather than the regular water, when you do this you will get pure deuterium.
Note that you will get very little deuterium from this water, you will need thousands of liters of water to make decent amounts of deuterium.
I'm sure there is other processes, but this is the one you can make at home, will take you a long time (and energy) to get a decent amount though.
Take a look here:http://www.youtube.com/watch?v=R_gAH3G7w4o
This guy explains it very well.