If I were still working, I would be targeting two tech fields: virtual reality programming and 3D printing. Modest sized 3D printers have been available at the consumer level for a few years. Most of these printers used plastic filament to print small gizmos and parts. But, what if you want to print something really big and useful... like a car?
Note that not all parts of the Strati were constructed via 3D printing. The engine, seats and steering wheel were manufactured in the conventional manner. The body, chassis and fenders were printed with thermoplastic using a big area additive manufacturing ("BAAM") machine.
The manufacturer, Cincinnati Incorporated, specializes in BAAM. They say they're able to produce a Strati in 45 hours for about $7,000. Here's a pic of one of their big area printers.
I recommend spending some time at Cincinnati Incorporated's website. It's a fascinating look at the most advanced, large scale 3D printing projects.
3D printing is no longer limited by scale or by type of material. If you look around, you'll find large scale printers that print with concrete and all types of exotic metals.
This is the sort of stuff that makes me wish I were still a young man, instead of a retired old grandpa!