system
Given the following post, respond as if you're commenting on Reddit:
human
What is the most scientifically feasible way someone will eventually build a working blaster pistol, phaser, or ray gun?

Or is it not possible? There are so many possible variations from Star Trek to Star Wars to Martian death rays to things like the proton packs in Ghostbusters. Are any plausible?

While I'm asking: how about a light saber-like device of some sort?
gpt
The main problem with a hand-portable laser right now is the power supply.  Currently, it takes a small truck-carried generator to get enough power to supply a reasonably deadly laser.  If someone invents a super-battery with thousands of times greater energy density, then we can have hand-held laser weapons.