If you are making up catalyzed methylmethacrylate monomer, it can only be
stored for a week, or it may not polymerize correctly.  That is why
large specimens are changed after 7 days, with a fresh mixture.  I 
routinely  make up infiltration mixtures JUST before use, some have
to be stirred overnight at RT, if not clear, refrigerate, and bring to
RT before embedding or water condensation will create havoc with 
polymerization.  It is important to remember that cold retards/slows 
polymerization, but PMMA can and will polymerize in a refrigerator,
it takes a while, but has that potential.     

I store stock mixtures for embedding in a brown glass bottle but prefer
to make up the amount needed, just before use, and never mix more than
500 mls at a time.  any stock solutions are used within the 7 day limit,
and for layer embedding of huge bones.  If I have leftovers for stock
storage, I bring to RT before use.  
  
Plastic containers, Nalgene also work, but they should be disposable - which
may force you to a cheaper variety of storage jars.  I often recycle my
brown wide mouth chemical jars or solvent jars for mixing/short term storage.

For embedding, I discovered some wonderful FLAT Bottomed containers,
normally used as formalin fixation containers.  You can purchase them
from Fisher, are called Histoplex, and come empty, in 40, 60, and 90 ml
sizes.  Erie Scientific now has a similar container, with even smaller
diameter containers.  one plastic container holds 15 mls, and all 
have volume markings outside.  The small one is wonderful!!  Perfect
for prepolymerized layers, which also tends to speed up polymerization.

If you use these plastic jars for embedding, in a waterbath for final
polymerization, weight down the lids or devise a way to keep water around
level of PMMA inside, it they tip over, suck water in, you will have a 
mess to die for!  



All these containers have O ring designed lids, which are perfect for
fume containment.  I will keep you email address, as my Erie Scientific
rep is to call back, he sent samples but no paperwork. 

Some people have used plastic scintillation vials, cut the bottoms off
and push block out postpolymerization.  Cheap!  Glass vials are dangerous,
in my estimation, since you have to shatter the glass off, then pick shards
of glass from everywhere, very unpleasant.