Introduction: Penrose Triangle (modified)

Picture of Penrose Triangle (modified)

This is a modified version of the Penrose “Impossible” Triangle which is an interesting example of how the brain can be fooled. The main difference in this version is the use of hardware to simulate the triangle side connections. Watching the video is the easiest way to see how it works.

Note that this is a very simple project. It took about 10 minutes and was “free” since I used pallet wood and recycled bolts. I’ve included a drawing which is included in the video description.

Step 1:

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  • Saw
  • Tape measure
  • Drill & bits
  • Sander (optional)


  • Wood (enough to make three 2” slats, 8” long)…I used one slat from a pallet
  • Wood glue
  • Lag bolts or something similar – used only for show

Step 2:

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Cut three boards – 8” long x 2” wide x ½” thick. Note that the size can be scaled up or down.

Step 3:

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Attach board together with wood glue – use a clamp to apply pressure

Step 4:

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Drill holes and add bolts/screws. Note that these bolts are just used to give the illusion that the wood is connected.

Step 5:

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I taped weights to the back side of the bottom piece to allow the triangle to stand upright. Other options include adding a center axle under the bottom to allow it to spin or placing holes in the bottom side and providing a matching plate with dowel pins. The second option would allow you to reposition the triangle in the exact same spot (relative to camera or person) which would be nice for video.

Step 6:

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I used a Canon DSLR camera for the photo and video. It took a few minutes on a tripod to line up the angles. I also had to use manual focus to try to pick a middle spot between the near are far pieces which helps with the illusion.

Step 7: Painted

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Also tried a couple of the photo suggestions mentioned in the comments.

Step 8: If You Like This, Check Out Another Example


dave1986 (author)2014-02-23

my brain hurts

mikenichols (author)2015-11-07

You're a PHONY! A big fat phony... But I like it.

sharpstick (author)2014-03-05

Nice. I;m going to make a slightly smaller one and put it inside a viewing box with a small pinhole viewing port that you can only see through with one eye from one angle.

I'll also taper the top piece slightly to allow for perspective, or it will appear wider than the bottom piece.

I agree with Algag. A smaller aperture and longer distance will increase the depth of field so the whole thing is in focus. Use the highest resolution, back off to ten feet or more to shoot, then crop the image down.

mtairymd (author)sharpstick2014-03-05

Sounds like a awesome idea. Please post the results after you make it

cvillanueva6 (author)2014-03-03

stop it and go home sir

jimmysymo (author)2014-03-01

It's the first time I've seen this ,and I said this IS impossible, Then saw the vidio

Fantastic ,,Will be making this tomorrow. thanks ,, Good for you.

Mixey 101 (author)2014-02-28

that looked like a triangle for a second then i saw what you did . so clever

alcurb (author)2014-02-26

Very nice and easy to duplicate. This one goes in my Favorites pile. Voted!

For your photography, may I suggest taking the photo with a long lens, like a telephoto. You'll have to move away to zoom it in. This way everything is thrown into focus with depth compression. Another way is to use a normal lens (no wide angle) and close the aperture as far as it goes to almost a pinhole, then compensate for the dimmer image with slower shutter speed, bright lighting, ISO speed, etc. The pinhole-ish aperture increases the depth of focus.

mtairymd (author)alcurb2014-02-28

Thanks for the photo suggestions. Hopefully, this looks a little better.

psavas (author)2014-02-25

Ever thought of outputting the CAD drawing into an STL file for 3D printing?

Johnkaye (author)psavas2014-02-26

Great Instructable but come on, really, you can't nail three pieces of wood together per the directions? You are actually considering 3D printing this? Far too many Instructables start off with 3d print this or that! Craftsmanship and skill seems to be a dying art.

Hey I was inspired by your comment and I just made a quick model based on this very instructable. It can be found here:

Very nice. When I get a 3D printer, it'll be one of the first things I try. Thanks!


mtairymd (author)psavas2014-02-25

I wouldn't 3D print this part since it only took a few minutes to build from wood. However, I do like 3D prints for parts that can't be easily machined - like this.

psavas (author)mtairymd2014-02-25

That's supremely awesome. :)

echoalex (author)2014-02-26

Wow ... Very cool ..

taggart01pd2020 (author)2014-02-26

it is cool

MixMixery (author)2014-02-25

You should use conical pieces of wood, so the open parts would look more realistic... at your picture their width is unequal...

Algag (author)2014-02-25

Not sure what kind of camera you have (that would actually be kinda creepy), but if you close (i think....) the aperture then more of the triangle will be brought into focus and it will be harder to tell the space in between the disjointed portion based on fuzziness.

mtairymd (author)Algag2014-02-25

Thanks for the tip. My son took the picture with a Canon T4i which I know very little about. With autofocus, either the front or rear came into focus which totally killed the illusion. I tried to use manual focus to pick a spot in between. I will try again to see if I can get a better picture.

doug21951 (author)2014-02-25


rimar2000 (author)2014-02-24


marsjer000 (author)2014-02-23

What video/ cad software do you use?

mtairymd (author)marsjer0002014-02-24

Autodesk Inventor

Ironwave (author)2014-02-24


Jayefuu (author)2014-02-24

Ha that's awesome.

Halphinian (author)2014-02-23

I totally fell for it at first! Awesome!

Kiteman (author)2014-02-23


About This Instructable




Bio: I like to design and build random things.
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