The "private planes" were liquidated from https://en.wikipedia.org/wiki/Universal_Hydrogen - "The company's main product was intended to be a conversion kit to be retrofitted to existing aircraft to allow them to run on hydrogen fuel."

The "massive 3D printer" was liquidated from https://en.wikipedia.org/wiki/Local_Motors - "was an American manufacturing company focused on low-volume production of open-source vehicles and other products using multiple microfactories."

If an investor accepted the premise of the companies, these don't sound like outrageous assets to own.