---
title: 'My Rock, Paper, Scissors Robot Never Loses (+9 Other Inventions)'
source: 'https://youtube.com/watch?v=Twn_4AW0M6U'
video_id: 'Twn_4AW0M6U'
date: 2026-07-22
duration_sec: 1156
channel: 'Mark Rober'
---

# My Rock, Paper, Scissors Robot Never Loses (+9 Other Inventions)

> Source: [My Rock, Paper, Scissors Robot Never Loses (+9 Other Inventions)](https://youtube.com/watch?v=Twn_4AW0M6U)

## Summary

This video presents a countdown of ten impressive inventions, ranging from a rock-paper-scissors robot to an infinite slinky staircase, with detailed explanations of the science behind each one. The host combines entertainment with education, breaking down concepts like ball bearings, laminar flow, and binary counting.

### Key Points

- **Infinite Slinky Staircase** [00:00] — An escalator-like mechanism that allows a slinky to descend stairs indefinitely, using a motor and feedback loop to keep it centered.
- **Screaming Chicken Heads** [00:25] — A choir of 22 chicken head noisemakers that produce sound when air is forced through them, similar to a kazoo or party blower.
- **Deflagration Tube** [01:11] — A device that creates a slow-moving wave of fire through tubes, culminating in a small explosion when the flame reaches the end.
- **Room Temperature Ice Rink** [02:07] — A surface made of ball bearings that mimics ice, allowing skating with almost no friction, and behaves like water particles in simulations.
- **Single Sheet Foldable Chair** [05:09] — A chair made from one sheet of material with a specific pattern, demonstrating that solid materials can be folded into functional objects.
- **Stroboscopic Water Illusion** [06:08] — Using a subwoofer vibrating water at 30 Hz and a camera recording at 30 fps to create a frozen wave illusion; changing frequency makes the wave appear to move.
- **Laminar Flow Fountain** [08:27] — A simple setup with a hose and drill to create laminar flow, which looks smooth and clear, unlike turbulent flow.
- **Nerf Gun Cleanup Robot** [09:08] — A robot that picks up Nerf darts using an acorn picker upper attachment, saving time on cleanup.
- **Simon Game Robot** [10:02] — A robot that plays the Simon memory game perfectly by using a webcam to detect lights and pressing pads with drumsticks.
- **Rock Paper Scissors Robot** [12:51] — A robot named Rocky that uses an IR hand motion detector to predict the player's move and throws the winning shape, achieving a high win rate.

### Conclusion

The video showcases a variety of creative inventions, each with a scientific principle behind it, encouraging viewers to explore engineering and inventing through resources like CrunchLabs.

## Transcript

This is an infinite slinky staircase that can run for days. Today we're not only going to countdown ten of the coolest things
But we’re going to also break down the science of how they work, Starting off at number ten, Typically, you'll have something like this
a choir of 22 screaming chicken heads. after you apply a little pressure
it will yield amazing results. We just need to take a look inside. It's basically just a kazoo or one of those party blowers.
it expands back to its original shape, and make that terrible, terrible noise. pressurized at 100 p.s.i, then you turn this valve...
It’s lunchtime! securing you a trip out to CrunchLabs
will show off his fancy deflagration tube. creates a slow moving wave of fire that spreads because of heat. And once it's almost done tracing all through the tubes,
with the oxygen, making a small explosion. And since the bottle is in the way of the quickly expanding gas, Now that’s only the first two
But number eight is where things really start to get interesting. it swallows you and then knock them over
You basically make a room temperature ice rink Isn’t it trippy?? as you can see here, it’s almost completely frictionless
Which means it should be perfect for skating
And while surfing, skating, and bowling it was ultimately so hard for us to keep our footing We decided to call in a Pro
And she’s a ten-year-old skateboard competition winning legend *snort giggle*
But, could she pull off the impossible jump?
Now, what makes Anna so great Can I still land it or no?
so before she take her final shot at nailing this trick Because intuitively, Because any given BB rolls smoothly on the ground
so when you have hundreds of these underneath you of perfect wheels to slide you in any direction. and then take your foot and also replace it with metal,
surface to itself like this, and the bottom surface to itself Well, now they'll still slide relative to each other. And this is exactly how ball bearings work.
They're in your bike, where the wheels connect with the axles. and a bunch of other tools
where smooth low-friction is required Another really cool thing we discovered they almost behave like water would, even though they're totally dry.
because when computers have to simulate water they break it down into particles like this. 1 to 1 match for a bunch of actual physical BBs, they are governed
Now back to Anna, who didn’t dissapoint
Now that we’d all survived number 8 But what makes them really cool is they're made from one single sheet then you give it a paint job.
very specific pattern. and then fold it into an actual functional chair. wood as foldable and bendy, but this is another example
when you could take advantage of the fact that even solid And just like with the world's smallest Nerf gun, and there's a 3D printable file in the video description
if you want to assemble your own mini single part foldable chair. at your end of summer block party. and it's connected to a subwoofer speaker.
up and down 30 times per second, But then if you set your phone camera it makes the motion virtually undetectable
your camera is only taking pictures when the wave is at So when you play it back, it looks like it's a frozen wave of water.
frequency to say, 31Hz or 31 times per second, is just a little further forward, and of course reducing the frequency
this can make you look like an absolute wizard. Theoretically, if you had a second speaker the combination should give you a spiral.
Now all that's left is to just play a sick beat to celebrate the W.
is you can make a very simple version of this yourself. and a bit then secure the hose
you’ll find the natural vibrations of the spinning drill near the magical 30 times per second rate, with the trigger will cause the wave
Now, a lot of people confuse what you're seeing here Because this is laminar flow. in a predictable pattern
The big difference is what you see, what the speaker is because the frame rate matches with the wiggle rate, but with laminar flow it looks cool even real-time with your own eyes.
you can make a simple version of this yourself too. tape a tic-tac-toe square like this even with these really simple materials
The next two inventions are pretty quick and simple. starting first at number five we place a platinum ticket inside one CrunchLabs Build Box.
You're coming out here to CrunchLabs in person. we'll have a very fun, epic Nerf gun battle.
What's not so fun, however, is the epic cleanup required afterwards. when you could just invent a robot to do it for you? of one of these acorn picker uppers and 3D printing an attachment
So with only the occasional empty working on coming up with other ideas myself and CrunchLabs have received
to put them on display in the front lobby in a trophy case. So the middle ground is if you stand right here it uses a 6 to 1 mechanical advantage pully system
And now, if you just so happen to look up And that brings us to the final three, starting with Simon, one of the most beloved games of my childhood.
and then you just have to repeat it back by pressing the same pad. another pad to the pattern, which just not so bad at first, but then it starts to add more and more and get faster and faster.
I think the furthest I ever me as a kid was like level 13. which means I have a very particular set of skills. skills that make me a nightmare for games like these.
from this incredible cockroach trap, each with their own drumstick, So these can be our pad smashers, but now they need to know
For that, we've just got a simple webcam here and it ignores everything in the camera rectangular portions where the bulbs are.
in any one of those rectangles, you know, So once you store those pad hits in memory to be played back Like, violently easy
is get through all 32 levels of Simon and while 32 seems like a random number of levels, there’s actually a reason for it bits were expensive.
and the number 32 is the exact highest number you can count to in Binary we’re half way there, so while my pad smashing robot just like all the things you've seen in this video so far,
you can basically make whatever you can dream up. because for kids we've got Build Box
they get delivered right to your door where Plus all the fundamental tools you need in your toolkit to start creating your own projects and inventions.
So this holiday season if you or someone you love the really fun and rewarding hobby of making stuff Just scan this QR code or head to Crunchlabs.com
feels like a moment... I’m happy to say
I finally beat this dumb game yellow His name is Rocky, and he's a robot who's really, really good
But before I show you just how good if you don't happen playing against other humans to win 75% of the time,
games of rock, paper, scissors and discovered a pattern. they're slightly more likely to stay with their previous choice, to the next in line of rock, paper, scissors.
If you win, go to the next one in the line in the order of Rock, Paper, scissors.. And if you beat them with paper, play scissors next So if lose with scissors, play paper, if you lose with paper, play Rock
Now of course, that doesn't mean you'll win every game, So if you just play best of 20, And as a man of science,
Again, I didn't win every game, Now, as for beating Rocky. much lower.
And that's because Rocky so he matches my movements up and down, using an IR hand motion detector
And then once the computer knows it, tells the correct to throw the winning shape. Or I go fast.
gets the $10,000 cash briefcase. the bullseye with the American Gladiators tennis ball cannon the bullseye with the American Gladiators tennis ball cannon
we built the CrunchLabs over the past year. Like most good inventions, the slinky was invented by accident a stabilizing spring off the shelf and noticed
So he and his wife decided to make a toy out of it, call it a slinky. And now, 80 years later, over 300 million have been sold. to see how many stairs in a row I could get it to climb down
now that I'm an engineer, it was time to avenge using a treadmill tilted at just the right angle. because the landing surface was inclined like a ramp
So to solve that issue, we tried an actual escalator and the speed was a little too slow. I could turn with a hand-crank.
You don't normally think about it, so they're coming up below you like this upside down. And that prototype worked well because we got the stair space dialed in
which is where these 3D printed self-centering cones came in handy the slinky would self-align Finally we got rid of the hand crank by adding a motor
so we could get the timing dialed in just right, of the slinky sort of varies slightly over time. we made a final version that looked beautiful
so it would run a closed feedback loop to ensure the slinky was always right in the middle of the staircase. But before the official demonstration,
Because if you let one hang down like this and then let it go, because it's balanced between gravity stays unchanged until the wave finally propagates down
And so without further ado, here it is. And so without further ado, here it is. these two buttons to temporarily slow down, or speed up the staircase.
After which the sensor takes back over, to adjust itself back to the middle I'm just going to leave this running to see how much I can beat that by.
This is now been running just over 48 hours, just over 208,000 stairs, which is just over 29,000 times more stairs than I ever got as a kid.
So I'm calling that a W in my ongoing quest to be the favorite uncle I’ve tried quite a few things over the years
But now I finally discovered a much easier way Or even parent a CrunchLabs Build Box subscription for the holidays
And then we build a really fun toy together Where you learn a new engineering principal Thinking like an engineer
Which means some day you too could be building robots your box has the chance to contain the platinum ticket Well then you’re coming out to CrunchLabs
in really fun ways with me just head to CrunchLabs.com or use the link in the description Thanks for watching