The Inka Pen is the latest attempt by a company to make a space pen, though this one seems pretty well designed, albeit rather expensive. Designed to be lightweight, watertight, and able to withstand harsh environments, the pen is made from high-strength aerospace-grade (what does that even mean?) materials, including carbon fiber and 304 stainless steel. The barrel is hardened, CNC machined, centerless ground then laser engraved. The ink cartridge is pressurized to ensure that the pen will write at any angle, any temperature, at any altitude, and even underwater (though no one yet has developed waterproof paper to write on, itâ€™s still a neat feature). The pen is made in the USA, comes with a lifetime warranty, and even uses recycled packaging made form 100% recycled PET and paperboard. I like the inclusion of a stylus, and the fact that this looks to be the only keychain pen that actually works like a regular pen, but did they need to add all of the aerospace mumbo jumbo? $25 will make you feel like an astronaut as you write on the ceiling, or $90 gets you the Titanium Inka Pen, so you can feel like the guy paying to be a space tourist astronaut as you write on the ceiling.