Ancient Artifacts of Stupendous Science

There are interesting gadgets that your players can find when prowling the wasteland, and then there are these things. They were rare and expensive before the Turn, and now they are the most prized possessions of the most powerful water barons, the sacred relics of hidden arcologies, or long lost in forgotten vaults.

Some might be a treasure in the big bad's lair, some a treasure the big bad seeks. Some will be the crux of their evil master plan.

All can surely be used for many a shenanigan.
  

A cruciform.
I've stolen this one wholesale from the Hyperion Cantos.
If you haven't read it, I highly recommend that you do.

 

d20 Artifacts

1. Bioprinter: From a single droplet of blood, this device can recreate and clone any creature. An adjustable fast-time field will even age the subject appropriately.
2. Recoiler: A piece of jewellery (normally a ring, bracelet or a brooch) that can be activated to instantly return the wearer to the safety of a pre-defined receiver chamber. Its range is long enough to bring one from Earth to the Moon.
3. Transmat cannon: During the Turn, these weapons were used to instantly teleport an armed antimatter bomb onboard an enemy vessel. It has a range of about a light second, a projectile chamber large enough to fit several people inside, and cannot be blocked by anything short of very advanced force shields.
4. Hypnolearning bay: A comfortable coffin where one can lie down to sleep and learn a new skill overnight*.
5. Phylacterion: A throne of chrome and wiring. When a creature is strapped into it, the phylacterion can either scan their brain and create a new mindstate disc, or download a mindstate disc into the creature's brain, overwriting their whole psyche with another person.
6. Cruciform: A cybernetic symbiont that bonds with the user and makes them nigh immortal. No matter how grisly their injuries or how little remains from their dead and destroyed body, the symbiont will eventually reconstitute them to full (physical) health. It's impossible to deactivate or detach, so users tend to be dealt with by chucking them into a volcano.
7. Becoming nook: Lie down into this surgery station and close your eyes as it anaesthetises you. One quick implantation later, you will be on your way to bionic ascension. No surgery roll is required and the recipient gains +4 bonus to their post-surgery Con Save if the becoming nook is used to add a new augmentation.
8. Warp star: A miniature black hole trapped in an indestructible crystal. Serves as an infinite power cell, capable of powering a whole city alone.
9. Gravity cannon: An unassuming platform that can nonetheless accelerate anything up to the size of a spaceship to a good fraction of c.
10. Phase gate: A cannon-like device that will charge up with 5D energy, then blast a hole to the next dimension over.
11. Nulltime tank: Inside, the time itself stands still. The grieving might keep their loved ones alive, for a certain measure of "life", while the decadent will always have their meals fresh and warm.
12. Replicator: A cloud of nanites in a box will break down matter on atomic level, then rebuild it into whatever their owner desires. While pretty much anything can be quickly fabricated, one still needs the materials and blueprints.
13. Matrix: There are many people with access to the Matrix, but this is the Matrix. Destroy this core, and the Matrix is gone. Or reprogram it to change literally anything inside. You can be a virtual god.
14. Humongous mecha activation codes: The chrome colossi of yore have lain dormant since time immemorial, but this could bring them back to life.
15. Sensory deprivation tank: The resting place for powerful psions. See here.
16. Regeneration tank: A sarcophagus-like medical device that can heal any injury, and even bring back the recently dead. Minor injuries disappear within ten minutes, a lost limb would regrow in an hour, while a resurrection might take half a day. When used to bring back the dead, however, they must Save with a penalty equal to the number of hours since their demise, or gain an insanity. Corpses that already started to rot cannot be brought back at all.
17. Time machine: When you climb inside, you can travel anywhere along the machine's own timeline, from the first moment it was activated to a split second before it will be rendered inoperable.
18. Docility drug formula: Dulls emotions, squashes all defiant thoughts. Easily spread through water supply. With a passable chemical lab, it wouldn't be hard to mass-produce the drug.
19. Small spaceship: One planet is not enough.
20. Stargate: Actually, you don't need a spaceship.

 

A phase gate, from Stranger Things.

*) Still subject to the limits on Memory.