If you ever thought it was called a "Dobb" kit, or spelled "Dop Kit", you are not alone my friend. The correct name and spelling is indeed "Dopp Kit" which doesn't, by itself, explain anything about how it came to be. So we did a little "Googling" and here is what we found:
From the Word Detective online, October 30, 2001.
"According to newspaper accounts unearthed by Merriam-Webster's Jim Rader, the Dopp Kit was first produced by Charles Doppelt, a leather goods designer who immigrated to the U.S. from Germany in the early 1900s. Although it may have been Doppelt's nephew and employee, Jerome Harris, who actually invented the snazzy leather toiletries case, Doppelt was the boss and so the finished product bore a cropped form of his name, giving us the 'Dopp Kit.' Dopp Kits were manufactured by the Charles Doppelt Company until the firm was purchased by Samsonite in the 1970s, and Dopp Kits today are made by Buxton. The popularity of Dopp Kits was evidently boosted considerably by World War II, in the course of which the U.S. Army issued them to recruits by the millions."