WWCF: Driverless cars or 3D printers in the average household?

Which will come first?

50%-household penetration for driverless cars

OR

50%-household penetration for 3D printers

News about both of these technologies of the future are in vogue right now. I've talked a bit about them here and here. The economic possibilities are quite promising. In fact, I see the factors slowing the progress of each to be more political in nature rather than technological. Regulators will be the first to cry, "Jane, stop this crazy thing!" Some of the very serious people are already sounding alarms about robot cars. Expect them to be joined soon by all those millions, and don't doubt for a second that it is indeed millions, of people whose livelihoods are threatened by a driverless future. For 3D printers the fears begin with guns and end with patent infringement run amok. Nevermind the fact that I've already solved the patent problem, et al. 

But back to the question at hand. While the Makerbot is selling like hotcakes, John Deere is already selling a driverless lawnmower. I say the driverless car edges out the 3D printer by less than five years, and I expect the 50% mark to be hit by the winner before 2033.

PS. With driverless cars you effectively don't need compulsory insurance or state licensing just as you don't have those conditions for guns, chainsaws, swimming pools, or outdoor grills. Good luck with that logic, though.