Marble Money / Paper Clip





Introduction: Marble Money / Paper Clip

About: I studied Maths and Computing, worked in an Operation Research department, retrained as a civil engineer, worked on site for some major projects. I'm learning to be a structural engineer at the moment! I've ...

I wasn't intending on entering the money clip contest, but as I was looking through all the current entries I found that all (bar a couple) seemed to be of a traditional design - using pressure from the 'bend' to hold the money in place. That inspired me to try and enter with a different method...

I made something similar out of wood and a marble when I was a kid so I know the theory of this works - so hopefully my 3D modelling does too!

Within the 3D model there is a 12mm 'ball'. You could use a marble of a similar size if you wanted to...

Date Made: September 2013
Approx Cost: (Cost of printing?)
Approx Time: 3 hours modelling (plus printing time)
Difficulty: Easy/Medium

Step 1: How It Works

There is a recess in the top runner - this recess is to stop the ball falling out.

Once printed, the ball (or marble alternative) needs to be inserted inside the 'runner'... This should just pop in (as long as the 3d printing material isn't too brittle!?!).

It is the pressure from this ball that will 'grip'.

The angle of the top runner means that 'grip' is adjustable - depending on the thickness of the paper inserted.

So to get the clip to grip, you insert the paper between the bottom (flat) runner and the ball. Then let the ball drop down to the narrowest gap (between top and bottom runner). Then slightly pull the paper back out - this will tighten and jam the ball between the top and bottom runner, holding the paper in place...

Hopefully that makes sense!?! I have done some sketches to try and help the explanation...

Step 2: The Model

I have built a 3d model, hopefully ready for 3d printing...

This was done using tinkercad and can be found on their website by searching for "Money / Paper Clip" or here:

Step 3: Optimization

I do not have access to a 3D printer, so am unable to try it out and to optimize the design.

If this model does not work very well (I don't see why it wouldn't), the next step is to analyse, evaluate and adjust the model.

Depending on whether the paper is not clipping or there is not enough room or something, then a number of alterations can be made to alter the design:

1. Make the ball bigger/smaller
2. Make the channel that the ball runs in deeper/smaller
3. Make the channel longer/shorter
4. Make the angle of the top runner bigger/smaller
5. Make the length of the runner longer/shorter
6. Raise/Lower the top runner compared to the bottom runner.
7. Make the arms thicker/thinner

There are lots of ways this could be personalised too; The aesthetics could easily be changed, adding patterns or designs or anything really.

The other thing to consider could be a way of mounting the unit (if you wanted to) - you could put a hole in the back so that it can be screwed to a wall, or you could put in a recess to allow a magnet to be glued in? Or you could just leave it on your desk or in your pocket...

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Money Clip Challenge



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    I don't have time to make another instructable at the moment, but here are a couple of bonus concept designs for variable money clips:

    Or go on to tinkercad and search for "money paper clip" and you should find them.

    They may work, they may not, and they aren't in a state you can print, but thought I'd share them as concepts anyway...

    Thanks, a place in the winners is always appreciated!


    Well, I wanted to stop by and say how great I think your idea is... Then I saw your MGB GT and now I'm thinking, "Gee", a British sports car aficionado... Just like me. This guy's REALLY cool. Good luck to you, my friend and think of me and my car, in the messy and expensive process of getting a body-remake. :/
    P.S. I voted for you.

    Screen shot 2013-09-06 at 7.14.26 PM.jpg
    2 replies

    Nice car. If that's your garage too, I'm even more jealous! I've had a couple of mgb's and built a lotus 7 replica too. No space for cars at the moment tho. Need a bigger house with a garage...

    Just looking at your pyramid puzzle. Might have to have a go at that...


    I wish... That's a 17,000 sq ft facility my local car club owns and where I store it. Thanks about the pyramid puzzle. Rather than hijacking your instructable, I'll PM you wit the details.

    I wanted to see the winning project in this contest. When I saw the shape of the money clip I was like seriously?; but it was when I acknowledged how it actually works I realized how awesome and golden this money clip project is.

    I didn't remember it being this big. My wife said it did have a magnet on it, but was not adhered very well. When the magnet fell off, she replaced with double sticky pads to hang stuff on wall. I may have a smaller version of this item around here somewhere, but I was lucky enough to find this on right away. And my wife reminded me that the guy made these to hold notes on the fridge--grocery lists, "I'll be back shortly" notes, etc.

    Cool. It's much bigger than the one I remember making. And I seem to remember mine being made of 3 pieces of wood not 2, but the principle is the same.

    The channel on it seems really deep. I'm wondering if the channel in my 3d model is deep enough to keep the ball in place now!?! Maybe someone will print it and give me some feedback, or develop the design.

    Thanks for the effort of finding and photographing it. Much appreciated.

    I took 2 photos but can't seem to upload them. Help?

    I've had something like this for over 20 years. It's made of wood and a large ball bearing with a magnet to hold it to a metal surface. I believe it was made to hold notes on the front of a refrigerator.

    2 replies

    Any chance of a photo? I'd like to see if it's similar to the one I made as a kid. Also it may inspire someone to make their own wooden version....

    Just found it. My wife got it at a senior center about 30 years ago. It had projects retired people made to sell. It's about 5 inches tall and about 1 1/2 inches wide. This one has double stick tape on the back of it.

    the tickets are normally 8.75 cm by 12.5 cm, and the ticket holder will hold 12-15 tickets stacked and they won't fall. you have to have a channel for the marble to ride in don't you so it doesn't roll out? if I ever get around a 3d printer I might print this, great concept. has my vote.

    this is the same way ticket boards in restaurant kitchens works.

    1 reply

    I didn't know that. Just looked it up, and they use ball bearings. I imagine that is because of the weight - probably a good option.

    They seem to be fairly short, I guess a ticket is only ever 1 sheet thick, so they don't need the variance?

    Hey this is rad! Can you attache the .stl file to your Instructable?

    1 reply

    I'm afraid I don't have a .stl file.

    I did it using tinkercad. If you go to it's free to sign up for an account, then you can find the model by searching (I made the model public so it can be copied and edited).

    I think you can download the file from there too - although I don't know in which formats...