Sprue is the solid, almost tubular bit of plastic which the individual parts are attached to when you remove them from the box ( it represents the channel down which the molten plastic flows in the mould ).

Usually it just gets thrown away, but if you warm it over a flame ( at the same time, gently pulling the ends apart ) it stretches thin and can be used for all sorts of scratchmade details ( eg whip aerials, weapons parts, etc etc ).

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