Do you have a tape head?  Wrap tape in a spiral on a large rotating cylinder.  Record music samples in an analog format.  Move the head to select the tracks.  Samples could be arranged on a musical scale.  Like a glass harmonica with tape hiss.

You might be able to turn them info ferrofluid, just look up how to do it on YT, or maybe make some money on fleebay, never know someone might pay for them.

They're LTO-3 tapes, yeah? I mean, how many do you have? I realize using them as designed isn't necessarily a "hack" but the LTO-3 tape drives are fairly cheap nowadays (if you're lucky, you can get a single drive for $100 or so), and if you've got data you can't lose, that's a great way to keep an off-site backup. 

Hmm. On that idea, make a DIY tape deck, using one tape drive and create a mechanism to store, index, and rotate the tapes as necessary. 

You could run it from a RPi, even. I'm sure there's some way to get a SCSI interface on a Raspberry Pi, and then just make a system that backs up your stuff off site. Combine that with a system to index, store, and swap the tapes in the drive, and that's a good amount of storage. 

33, but I don't want to bother with backup, I like to live dangerously!

I think you make ferrofluid using the tape

* VERY long loop recording, like days of echo delay. Call it "echo a month".

* Make a raft where you use tapes to tie wood, call it raft consensus.

* Make large cardboard dart, tie one roll of tape to back perpendicularly, toss it from large tower to make the biggest sepentine in the world. Dart is so that roll doesn't start to spin.

* Coat tape with photo emulsion, make slit camera and record the biggest panorama in the world by driving some road and synchronizing tape with your car.

* Make confetti and call it "random access memories".

* try making some constructions by hot-welding the tape into various shapes.

* make tensegrity table held by tape (with multiple strands of tape maybe).

* check if you can sharpen a knife by running tape over edge.

* fill it with a video of rick astley

* see if using a hundred of several meter strands will make for a good foil-strand parachute

* make a rope bridge, call it "bridge to terabithia".

P.S. I would like to know what could I make from 2 thousand sim-card carriers (those credit card sized bits of plastic with hole after taking out small sim card).

@Krzysztof You can cut 3d puzzles like ships or cars for board game. Like this: https://pirateswithben.com/

So many amazing ideas, Hahahahahah