Dougong, an Ancient Chinese Technique

For this instructible, I have decided on making a miniature model of the dougong timber structural system. It will be a 7 layer bracket and bearing block system that will display the beauty and complicity of the Dougong.

What is Dougong?

Dougong is a structural system of interlocking wooden brackets used in traditional Chinese architecture to support roofs and transfer weight of the roofing, the above floor etc. "Dou," which are the bearing blocks, and "Gong," which are bracket arms, are connected by mortise-tenon joints. Dougong plays a crucial role in both the structural integrity and decorative elements of Chinese architecture, particularly in high-status buildings like palaces and temples.

The Dougong technique dates back all the way to the "Spring and Autumn" period (roughly the first half of the Eastern Zhou) which was at about 770–476 BCE (Ancient History).

The interlocking blocks were solely fitted together by joinery without the usage of any glues or nails!

The Approach:

step1 - Do some research.

step2 - Informative video.

step3 - Create the 3d model.

step4 - Adjust the model for 3d printing.

step5 - 3d Print the models.

step6 - Assemble the model.

The List of supplies required for this project are:-

1. Fusion 360 app.
2. 1kg PLA filament.
3. 3d printer (I finally got a 3d printer yeee!).
4. A laptop.

We are good to go!!!

To begin any project we must first research about it in detail. Not only does it gives us knowledge related to our work, it also makes things a lot more easier as it will help avoid mistakes. This research is in two parts, that is the 'Dougong' which is our star of the project and a smaller research on how to 3d print. (as this is my first time 3d printing and I will share the things that I felt was very helpful).

The Dougong System:

Since it comprises of multiple brackets and bearing blocks, we need to choose a model that is not too overcomplicated and something that is not too simple.

It was developed over 3000 years ago and was assembled using the traditional wood joinery method of "sunmao". The Dougong has been an essential core of architectural design during the Qing dynasty. It was originally had to be attached to a column for support but later became column free.

It was manufactured under a master carpenter who would draw, plan and create the templates for the required blocks. The many carpenters would carve the universal dougong components and less skilled workers would assemble them layer by layer. Finetuning was required when building to overcome the small handmade inaccuracies.

The dougong was assembled in such a way that it had a little 'give' in the structure so that in case of an earthquake, the entire bearing and bracket blocks would vibrate (or move a bit) to prevent failures due to brittle joints. As a result, dougong system such the 'forbidden city' palace complex has stood to this day with very minor damage from earthquakes over centuries.

https://iopscience.iop.org/article/10.1088/1757-899X/960/2/022008/meta

https://www.sciencedirect.com/science/article/abs/pii/S2352710223003042

https://www.sciencedirect.com/science/article/abs/pii/S0950061821033882

My Model:

The Dougong model I choose is from the "Temple of Solitary Joy" or the "Dule Temple" located in the Jizhou District of suburban Tianjin, China. It is a part of the front main gate(Shanmen of the temple) of the corner section.

reference:-

https://en.wikipedia.org/wiki/Dule_Temple

https://www.youtube.com/watch?v=JnB3fQTE1XU&list=PL-RkSAa8C6TTznGqk-XEmKtMd6aLJeSdC

A small video explaining how a dougong system works!

Video Credit : - Wooden Legacy

From here I will be creating the 3d Model in Fusion 360.

It may seem complicated... but trust me, once the basics of fusion360 (or any other 3d modelling software) is clear we can easily make any shape or a combination of shapes.

It is in how we can approach a particular design in 3d is what is the most important part, after all the end result will be the same and no matter which path or technique we take to approach it, it will become much shorter and easier as we keep doing it. we learn new ways!

Also, I would suggest to see the video as there are a few complicated shapes which are hard to explain by words.

Hope you this was helpful!!!

The Base block is the focal point of the bracket set and it sits directly on the column.

1. Create a square in the x-y plane. (select a plane or a 'flat' surface, right click and then 'create sketch')
2. extrude the square.
3. choose a plane on the sides of the extruded square perpendicular to the base it and draw an arc.
4. cut out the arc.
5. use the pattern tool and select 'circular'. Select the curved side and choose the 'z-axis' as the axis and set to 4 parts. --- this copies the cut action of the extrude that caused the curve to be applied to all sides as a pattern. (This can be achieved using mirror tool too, but this is faster)
6. select the top face of the part and then right click and select 'create sketch'.
7. then draw out the cut outs and the features that needs to be extruded as shown in the video.
8. extrude and done!

The Base is complete!!!

For Tier 1 and 2, I did the following:-

1. For tier 1 I selected the plane that is perpendicular to the top face of the 'base' and created a 'new sketch'.
2. Then I drew out the outline of the 'side view' of the bracket as it will be the easiest to approach its shape.
3. Then I extruded it to the required thickness and then chose a side of it of the "dou" part above the beams.
4. here I simplified the design and made only 2 small extrusions as the bearing blocks as designing each and everyone would be time-consuming and my printer may not be able to print its great details.
5. I made sure that the ends of the beams had a curve by selecting a side-face and then drawing the curve and extruding ('cut' option) it.
6. for the upper tier I did the slightly similar thingy but made the beam or 'gong' part a bit longer proportionally to the lower tier.
7. For the bearing part I did the exact same for it to be the same dimensions.

Now that the base symmetrical beams and the longer non symmetrical beams are done I will be reusing them for the upper tiers and done in the real one.

To make its centre of mass perfectly on the center of the base block I had to make a few adjustments at the very end after recording all the videos.

Tier 1 and 2 is complete!!!

For tire 3:-

1. I reused the beam from the bearing block and made it a bit longer by using the 'split body' tool in the 'modification' tab. To use it, I selected the extruding part of the bearing block and then selected the 'body' to be split and the 'splitting tool' which is the surface perpendicular to the side of the beam.
2. after splitting the beam, I increased its length to match the proportion of my reference by extruding the face of the cut part.
3. after making 3 equal parts and 1 longer one which will go through the middle.
4. to make the slots that will hold them together, I first arranged them in position and then selected the first two in order (i.e. the one that would go at the bottom and the one on top of it).
5. then I chose the top of the bottom piece and created a sketch on the surface. While in the sketch, I selected the over lapping lines of the next piece and while all the lines are selected (use 'ctrl' to multi-select), I pressed 'P' of project and the overlapping lines becomes a part of the current sketch.
6. then I extruded only the first block down until only a bit was left. ( If two objects overlap and we need to cut only one of them, we can do the following: 1. hide the other body in the view menu, 2. under the 'cut' option of the 'extrude' tool display there will be a list of bodies it will cut through simply deselect the one we wish not to cut.)
7. after that I used the 'merge' tool in the 'modification' tab and chose : cut, keep tool.
8. repeat for all the blocks until all of them fit snugly without overlapping.

Tier 3 is complete!!!

For this tier, it is the same concept as before.

the only new parts are the cylindrical purlins and the beam that sits on top.

The main tools are: extrude, mirror, sketch, pattern, move, and copy.

if we learn these tools, then any shape becomes easy to approach.

Tier 4 to 6 is done!!!

The 3d model is complete!!!

Here is the Fusion360 file (.f3d) of the finished model.

This is for FDM (Filament Deposition Method) Printers!!!

Before 3d printing we need to keep a few things in mind:

1. Accuracy of our printer.
2. Size (scale) of the print (of each part).
3. If there are inserts or parts that couple/joints.
4. How much detailed is the model.

Accuracy-

The printer accuracy plays an important role in how detailed and how much margin of error your print will have. The more accurate the printer the better will be your design. Also we do not have to adjust for the error margin if our models have precise (and small) parts.

Size/Scale-

If your model is big, then it can be printed in parts. If it is a must to print in one go, then your printer's bed size plays an important role. bigger bed size means we can fit more detail onto each part we print instead of simplifying the part and printing it small. As very small prints can cause that bit of detail to fail after printing.

Inserts/Joints-

One of the most important stuff in 3d printing. While designing a part which goes in a part, for example, a solid cylinder that goes in a tube, the outer diameter of the solid cylinder will be the same as the inner diameter of the tube and when we move the solid cylinder in the tube, it slides in perfectly without overlapping. This is not possible in the real world as a ring with the same diameter of a rod cannot be fit!

It is like taking 2 mugs with the same diameter mouth and trying to fit one in another. This is crucial in 3d printing as after the print, we may be all happy but instantly regret it when our parts do not fit. This is extremely frustrating as some parts may take a very long time to print depending on the design and size (5+ hrs).

Hence before 3d printing it is recommended to slightly reduce at least one of the surface that comes in contact in a insert or a couple. (if it is just two shapes touching each other, then it is fine)

Details-

The more detailed your model is the bigger you may have to print depending on the printer accuracy. For example: my printer has an accuracy of 0.2mm which means for a detail like a small extrusion or a vein on a leaf or a small peg that may hold another part I make it about 1.5 to 2mm minimum so that it will be strong and clearly detailed.

Do not worry about all the dimensions when working over a 3d model, just have a rough idea of how large the end product (printed) is and then do the modelling(This is important, if you forget your printer's limits, then you maw have to redo it all!!! ). after your model is complete, use the "Scale" tool of your respective software and scale according to the required conditions. (This is what I did for this model)

Now to print it, we need to know how 3d printing works

From here it is all about printing the parts till we get what we like!

If you see 2 different printers here, that is because the first one went KaPuT! and had to buy a new one... Hence always research before buying a new one for reviews and quality. (I recommend the Bambu labs a1 mini for beginners).

After setting up the printer (With the help of the manual or through YouTube), to print a model we need to convert our model into '.gcode' which is a type of file that the printer can understand.

To do so:-

1. Download and open the slicing software (Usually the printer may come with its own software, here I am using Bambu Studio which is compatible with most printers).
2. Select the printer that you have, if it is not displayed, then you will need to select 'generic'.
3. Set the nozzle diameter (usually in 0.2 - 0.4 mm) and the type of filament you will be using. (PLA is best for beginners and in general is very easy to work with)
4. Then in the 'strength' tab if you scroll down, there is an option for 'infill' pre-set at 15%
5. What is 'infill' ? :- well, it the amount of filament that goes in the "volume" of your model. i.e. if your 'infill' is 100% then the printer prints the model as a solid piece (Which can consume a LOT of filament and Time) usually up to 15% infill is good enough for strength unless you are going to use the model for holding weight etc.
6. After that in the 'speed' tab make sure that the "slow down at overhang" is selected. (This tab appears only if you select the 'advanced' option.
7. For small overhangs and bridges, the printer can print it without support, if your model has a lot of distinct and large overhangs, then preferably use 'support'.
8. After you are satisfied with the settings click on the 'slice plate' option on the top right. The software will slice the model and also show how much filament is required and time it will take to print (It is usually quite accurate).
9. Export the .gcode (Top right) and then put it on a SD card (printers usually come with SD card and a SD card reader, if not buy one you will need it)

You have successfully sliced your model!!!

To Print simply insert the SD card in its slot and select the model from your printer and press/select 'print'.

The parts are assembled layer by layer on and then put on top of the Column... so that it won't collapse just in case. After that it is pretty stable.

I did made a few mistakes in the balancing the model and it became back heavy... and I came to know that when I printed it out. I corrected it and have put the corrected .stl files so that if you need to print them it should come out perfectly, snug and the centre of mass on the center of the column/pillar. (Guaranteed!)

DONE!!!

This project has been an awesome journey into the fusion of traditional architectural engineering and modern 3d printing. By creating a miniature 3D-printed model of the Dougong system, I’ve not only deepened my understanding of ancient Chinese craftsmanship but also learned to adapt it through modern tools like Fusion 360 and FDM 3D printing.

Dougong is an elegant and ingenious joinery system which represents centuries of architectural wisdom. Recreating this structure taught me the value of precision, modularity, and balanced design—concepts that remain just as relevant in today’s architecture and engineering.

Throughout the process, I encountered several practical challenges—from understanding the Dougong's mechanical function, to ensuring printability, fit, and balance in the assembled model. I learned to account for 3D printer tolerances, to plan around overhangs, print resolution, and to create interlocking components that actually functioned without adhesives—true to Dougong tradition.

In conclusion, this project helped bridge the ancient and the modern, and I believe this kind of effort contributes meaningfully to both the preservation of cultural heritage and the advancement of modern design methodologies. It has given me a lot of knowledge and skill for future work—perhaps even scaling up or exploring more dynamic architectural mechanisms from history.

Thank you so much for your time!!!😊

References I used:-

1. https://www.youtube.com/watch?v=JnB3fQTE1XU&list=PL-RkSAa8C6TTznGqk-XEmKtMd6aLJeSdC&index=2&t=460s
2. https://www.youtube.com/watch?v=BcNc6nP__6U&list=PL-RkSAa8C6TTznGqk-XEmKtMd6aLJeSdC&index=2
3. https://www.youtube.com/watch?v=QU1iZCPtzV0&list=PL-RkSAa8C6TTznGqk-XEmKtMd6aLJeSdC&index=4
4. https://iopscience.iop.org/article/10.1088/1757-899X/960/2/022008/meta
5. https://www.sciencedirect.com/science/article/abs/pii/S2352710223003042
6. https://en.wikipedia.org/wiki/Dule_Temple
7. https://www.sciencedirect.com/science/article/abs/pii/S0950061821033882
8. https://www.youtube.com/watch?v=T-Z3GmM20JM&t=202s