Hi Tim:
 
I've never seen the plastic molded stuff for shallows, now that you mention it.
 
How many shallows do you have?  I had a couple dozen a few years ago, as
out in Massachusetts the hobbiests generally used just shallows.  Out here
in NY (and probably since in MA), the preference is usually for the
mediums, which hold substantially more honey per box, still without being
so heavy as a deep.
 
Anyway, my shallows ended up being converted to cobana (round section) -
depth supers, by cutting them down on a table saw.
 
Others were converted to mediums by nailing a rim to the bottom, making
them 6 5/8" deep.
 
It's nice to have all the supers uniform, and it can really expedite things
like returning newly-extracted frames or sorting combs.
 
Seeing as how frames are CHEAP (commercial grade will run only 35-40 cents
apiece in lots), why not just change them to mediums, and supply plastic
foundation OR, perhaps better still, the one-piece plastic frame&comb
units?  You can just ditch the shallow frames (good kindling!) or save them
for spare parts.  They really don't hold much honey, as the top bar is so
thick in comparison to the comb depth.
 
On the other hand, the plastic frame units hold even more honey than
regular medium frames, as the plastic "top" and "bottom" bars of the molded
frames are very thin.  You end up with substantially more cells (and
volume) than with any wooden frames.
 
Food for thought anyway.  I just figure if you are going to put all the
effort into installing fdn in the shallows, maybe it would be more feasible
to change em to mediums while you're at it.  That's what I've done, anyway,
and I've found it beneficial.
 
Best wishes for 97
 
Joel Govostes            Freeville, NY  (near Ithaca / Cayuga Lake)