By weight mix 7 parts sugar, 3 parts corn syrup and 2 parts water. Add
food dye to colour, or use brown sugar for brown glass. Heat until it
melts/dissolves at 225F or 108C. Let it cool - as it starts to harden
pour it into the mould, then tilt the mould to cover all the surfaces.

Monta Elkins found that this didn't work at 225F, but 300F worked well.
Also, use the clearest corn-syrup you can find, as the slight yellow
colour shows in the completed glass. Adding vanilla essence makes the
failures taste good enough to eat.

Dave Porter suggests covering a bottle with a carefully smoothed layer
of foil, then many more layers of possibly crumpled foil. Cut this in
half and use it as a slip mould for toffee glass bottles.

Be wary of hot sugar syrup. It hurts. Use gloves.

Toffee glass is hard to get right and incredibly messy when it goes
wrong. A number of people have recommended using casting resin to make
breakaway glassware instead.

ANA have been recommended for breakaway bottles, furniture etc.

ANA Special Effects
7021 Hayvenhurst Ave.
Van Nuys, California 91406
(818) 909-6999

Another source for breakaway resin (ordinary polyester or epoxy resin
isn't any good for this) is:

Zeller International
Main Street
Downsville, NY
USA 13755-0375
tel 607-363-7792

They have a catalogue and price list of their breakaway and other SPFX
products.