From Discworld & Terry Pratchett Wiki
|Death||dropped in his own vat of rubber|
|Books||The Fifth Elephant|
Wallace Sonky (Deceased), in his time created items (known as sonkies) designed to keep the population of Ankh-Morpork down. Sam Vimes was heard to say that "the housing shortage in Ankh-Morpork would be a good deal worse if it wasn't for old man Sonky and his penny-a-packet preventatives". Though some dwarfs like Captain Carrot have "views" about sonkies, Mr. Sonky seems to be doing a brisk and lucrative business.
Sonky's products are free to all City Watch employees, on the basis he didn't want more watchmen produced. They sell for a penny a pack and do not come in fun flavours like Cheese and Onion.
Buggy Swires buys the "Big Boys" as and when he has to. From the point of view of a gnome, they make excellent waterproof macs for rainy nights.
Sonky came to a rather rubbery end in The Fifth Elephant when he was found in a vat of his own molten latex, producing a life-size, full-body Sonky. It is related in The Compleat Discworld Atlas that the father of Wallace, a salty old seaman, brought the secret of rubber back with him from Ghat. His idea was to make childrens' toys with it such as balls. The nearest he got to his son's brainwave for the product was to make a watertight rubber container capable of holding seamen. Wallace continued making inflatable dinghies but, possibly by association of ideas, took the family firm in other directions.