3D printing is a fantastic, growing market.
But back in the early 1900's the automobile was an industry poised for tremendous growth. It would have seemed wise to invest in a few of the early companies, and just watch the money roll in. Which ones would you pick?
Would you have been smart enough to pick GM, Ford or Chrysler? Or would you have picked from this list? SPOILER ALERT - there are over 100 companies in that list that never made it into the 1930's. And that is just from the companies whose name started with "A"!
List of defunct automobile manufacturers of the United States - Wikipedia, the free encyclopedia
And in case you think I'm cherry picking with the letter "A", not even picking a less common letter could assure success:
Zent (1900–1902, 1904–1906)
Good Luck! (How about an index fund instead?)