I was involved for a few years in developing a large vacum casting
system for a sculptural foundry and I developed a system for getting
flasks in and out of a top loading kiln. To give you some idea we
were using flasks up to 20" high and 10" across, some used 3-4 bags
of plaster each.
To lift in and out I drilled a pair of 1/4" holes 1" in from each
end across the widest section, ie a diameter. Then cut a piece of
1/4" stainless steel studding 2" longer than the diameter and bolt in
place inside and out, this is the bottom of the flask. The other end
use 1 1/4" ss bolts with the heads on the inside. To lift you make a
strong wire loop like a bucket handle only with the little loops at
the end twisted to go sideways I still use a bucket handle for one
size of flask!).
You can drop the flask over your wax model quite easily, and the
studding supports the plaster at the open end. There is obviously a
lot more to it than this, the foundry went on to LARGE perforated
flasks but I still use my system to great effect.