What's your favorite science fiction device (that isn't a weapon)?

[Lord Joeltion]

*any device by which something we would consider "supernatural" is harnessed and controlled like any other phenomenon (proton packs and other ghostbusting equipment, the sunlamps and other troll hunting equipment from The Troll Hunter, Hex the arcane computer fron Discworld, the No Chambers from the Dune series, etc) or mass produced as if it were an ordinary thing (the gag factory from Roger Rabbit, the mass manufactured bound-demon powered watches from Discworld, etc)

Laughter Energy from Monsters Inc. would be awesome too. Then again, I fear we would spawn a new cross-breed of environmentalists/SJWs attempting to police over what kind of jokes bring the less pollution

You'd also die horrifically when the safeties malfunctioned and the tutor turned murderous.

I would fear more for my safety during Kinky Time, to be honest. You don't want a murderous Black Widow at the worst possible time

.Judging by how troublesome and dangerous the holodeck seemed to be, episode after episode, Starfleet personal must've been really dependent (addicted?) to it.

You mean you wouldn't?