The Quick and Dirty:  Prep your "victim" by shaving any hair that they will let you, then apply vaseline lightly on the skin and heavy on body hair (I recommend shaving body and armpit hair instead).  Get 2-20lb. bags of plaster of paris,  3 yards of loose weave burlap, 2-8 foot long 1"x2" pine wood (cut in half),  2-5gal. buckets.  Cut 2 yards of burlap into 4"x10" strips and leave 1 yard intact.

1. lay your prepped "victim" down on some plastic (this gets messy!)

2. fill each bucket with 1 gal. of tepid water about 80 to 90 degrees.

3. With your hands, gently sift the plaster into the water.  Let the water absorb the plaster until it looks like a dry cracked riverbed.  Do not agitate!  Do the second bucket with a bit less plaster. let it reach the top but not as dry and cracked as the first.  Do not agitate! If the plaster is not stirred it will not set up, you want it to stay in a liquid state until you are ready to use it and then you will stir it.  Do not move or bump the buckets.

4. Vaseline your arms and mix the first bucket by hand stirring for about 3 minutes. Let the plaster "cream".  Plaster will start out like milk after it is mixed and after it sits for a bit it will cream, becoming thicker. This should happen within 5 minutes.  Check every minute or so.  When it has creamed, slather it on your victim rubbing it in with you hands, then dump and spread it about 1/2 inch thick all over the chest.  Do this quickly.

5. Immediately mix the other bucket for about a minute or so. Dip your burlap strips into the bucket, pulling them in between your fingers to remove the excess. Lay and smooth them onto the first layer of plaster. Don't push to hard and press it into the skin. You will have to work quickly to cover the torso with burlap strips and finish it off with the large piece of burlap. Save some strips to attach the 1x2"'s to the top of the mold lengthwise as handles and reinforcement.

Notes: You want to finish your second layer before the first layer hardens, this will prevent cracking.  Keep the mold no more that 1 & 1/2" thick or it will become to hot and heavy
for your victim.  Let the mold heat up and start to cool before you remove it, unless it
becomes too hot for the victim; it should be ok as long as it has started heating but the longer the better.
Be careful not to let the plaster wrap behind the sides too much or you will have undercuts and will have a hard time getting it off with out cracking, just wipe the side as you work.
Tell you victim to use shallow breaths when the plaster starts to harden to prevent cracking.  Work fast and don't press too hard after the first layer to prevent cracking.
An even thickness makes a stronger mold, you can do additional reinforcing after the mold is off.  Two people makes this a lot easier!

Clean out the mold with a little acetone to remove all the vaseline residue and let the mold dry for a few days  The drier the mold, the better.

Tint a gallon of latex with some proline tints to a light flesh tone, remember latex dries much darker. Pour the entire gallon into the mold and quickly brush it all over, tilt and slush it around. If you have enough latex to fill it up, do it. You want about an 8th of an inch thickness, the plaster will absorb the ammonia out of the latex causing a skin to form against the surface, so keep slushing and brushing until you get the desired thickness. Pour out the excess, let the latex cure for 24 hours. At this time you could poly foam fill or fiberglass back your latex piece depending upon your needs. If you had any bad air bubbles in your mold you can fill them with water based clay and blend with a damp sponge prior to casting the latex.

Demold and paint!