I have used this method for some years, and it works well.  Just a couple of
notes regarding the solvent that Dr. Clench recommended.  I use a lot of
xylene here in the lab - on the order of 8 to 10 gallons a month.  As
organic solvents go, it is a relatively safe one, with toxicity and
flammability characteristics comparable to kerosene.  But you shouldn't use
xylene - or kerosene - without good ventilation - or near sparks or open
flames.  Don't smoke!  Protective gloves might sound like a good idea -
however, xylene will dissolve latex, rubber, and many plastics.  You can get
by without gloves if you use some kind of tongs or forceps to dip the
shells, not your hands.  I would take exception to Dr. Clench's
recommendation to heat the xylene.  Any liquid heated in a tightly sealed
container may burst the container due to thermal expansion of the liquid;
and xylene heated in an unsealed container will fill your house with
strong-smelling vapors.  Even at room temperature it is rather odoriferous
(again, comparable to kerosene).  The paraffin will dissolve in the xylene
without heating.  It will take a little longer (maybe overnight, compared to
an hour or two), but heating xylene isn't a good idea unless you have a fume
hood to work in.

Just noticed - Dr. Clench refers to the solvent as xylol - same thing.

Paul M.