For the caveman on your list or anyone who enjoys historical drinking chalices, the 'Das Horn' drinking cup is a perfect addition to anyone's cave.
The 'Das Horn' is described by its inventors as a "modern twist on the ancient drinking horn," which is exactly what they've produced. The cup itself is produced using BPA-free plastic and can hold up to 24-ounces of liquid, which makes it a great alternative for switching up cups at a party or get-together. Neck straps and stands can be purchased separately, while those wanting a personalized chalice can opt for laser-etched engravings.
The creators of 'Das Horn' have created a promotional video that ensures that the cup has been created without any harm towards unicorns, narwhals or endangered white rhinos.