Inventors killed by their own inventions:

A list on wikipedia, including:

-Henry Winstanley (1644-1703) was killed in a storm while inside the lighthouse of his own design, after expressing a wish to be inside it during "the greatest storm there ever was."

-Thomas Midgley, Jr. accidentally strangled himself with the cord of a pulley-operated mechanical bed of his own design in 1944.
(It is worth noting that he also invented leaded petrol and may well have died from polio (had he not been killed) which was attributed to him being weakened by lead poisoning.)

-Contrary to popular belief Joseph-Ignace Guillotin, the supposed inventor of the guillotine, did not himself directly invent it and did not die by it, nor did Haman invent the gallows — he was simply hanged on the particular gallows he had built.