Théodore Olivier’s string models of descriptive geometry – DIY version

This past summer, I visited the Musée des Arts et Métiers in Paris for the first (but oh my god not the last) time. It was incredible from top to bottom, I spent hours there and could have easily spent many more, and I can’t wait to go back.

The collection is a repository of industrial inventions and scientific instruments. Lavoisier’s actual lab equipment, Pascal’s actual calculators, and Foucault’s actual pendulum are just right there hanging out. How have I not heard of this place until now?!

The top floor is a collection of antique scientific instruments – completely breathtaking and worth the price of admission all by itself. One of the exhibits that particularly captivated me was a collection of models made by Théodore Olivier. In the mid-1800’s he made a series of models using string to illustrate various geometric concepts in 3D. There are a bunch of them and they are gorgeous:



I was so inspired by them – I was dying to get behind the glass and turn the knobs and play with them. And open that wooden box and see what’s inside! I knew intellectually that each of those red strings was a perfectly straight line running from the upper circle to the lower one, but seeing the beautiful curves that they made in aggregate made me want to make a model myself so I could really really believe it.  I didn’t have the time, tools, or skills to duplicate this with the brass fittings, but the dovetail construction on the box gave me an idea for cutting out something similar with a laser cutter and make my own mini-version.

Step one, design the parts and cut them out with with the laser (at TechShop – one of the best places in the city – go check it out!).


Having very little box-making experience, my first attempt was diagonally challenged:


But after two more tries, I came up with a simple design that would support itself at right angles:



The shape was solid, but the burnt edges from the laser were distracting. So I spray painted the whole thing. Gold, because I had some.

Finally time for some string! Now I could really see each string going in as a perfectly straight line. It was great to see the curves forming as I made my way around the circle.


Once I had gone all the way around, I had a passable version of Olivier’s model:


There were 24 holes around the circle. I’m not sure why I picked 24 except that I had a vague notion that the 12 hours on a clock face wouldn’t be enough to really describe the shape, and 30 was too many for the small-scale model I was building.

I played a bit with the number of holes to offset the string as I went from top to bottom. If I had run the string vertically, I would have ended up with a simple cylinder (see Olivier’s original model above) and going directly across (12 steps) from the originating hole would cross directly over the center of the model and would have given the silhouette more of an “X” shape than the cool curved “waist” I was after. I ended up offsetting each string 9 holes from top to bottom.

Seen from the top, there’s a perfect circle in the middle:


I was really happy with the result and it made me want to make more of them. Olivier made tons and they are so beautiful – check out some images here. I’d like to try some more at a larger scale and maybe even add some moving parts so you can change some of the parameters of the shapes as you’re looking at it.

Okay everyone – go make something!