What Sci-Fi gadgets do you want to see in real life?

We already have them. They're called coloured tubelights (very effective when eliminating Darth Insects).

I'd love myself a good solution for mass interstellar transit. Pick the O Neill cylinder seen in Interstellar for now. A time travel machine would also be fun (although I assume it would be disastrous).

Lightsabers, obviously.