3D Printing a QR Code (Adding it to a model meshed with GS2Mesh)
Introduction
In this post, I tried adding a QR code to the Haniwa 3D model I previously output using GS2Mesh.
I have a few acquaintances who 3D print QR codes, and I was always surprised at how accurately they could be output. Since my Haniwa model happened to have a flat base, I decided to try adding a QR code to it.
▼I’ve been making Haniwa models like this one.

▼Previous articles are here:
Repairing the Model in Fusion 360
I previously used Blender to adjust the models output by GS2Mesh, but for adding the QR code, I used Fusion 360, which I’m more accustomed to.
▼I am using a gaming laptop purchased for around 100,000 yen, running Windows 11.
▼This is what it looked like when I first added the model. There are hollow parts and missing sections.

▼An error appears stating that the mesh is not closed.

First, I need to resolve this warning. Clicking the yellow triangle icon opens the repair tool.
▼You can change the repair type.

I tested several repair types to see how the preview would look.
▼Here is "Stitch and Remove."

▼Here is "Close Holes." It looks like there are a lot of meshes on the bottom.

▼Here is "Wrap."

▼"Rebuild" seemed to produce the cleanest model.


I went ahead with the "Rebuild" option.
▼The mesh is now closed.

Next, I converted the mesh into a solid body.
▼I converted the mesh using the "Convert Mesh" tool in the Mesh tab.

▼It has been converted into a solid.

Adding the QR Code
I prepared a summary page for 3D Gaussian Splatting related articles, so I’ll generate a QR code for that page.
▼This is the page:
▼I generated the QR code on the following page:
https://qr.c-cloud.co.jp/tools/generator/design
▼You can change various parameters.

▼I learned for the first time that there are parameters like the Error Correction Level.

I exported it as an .svg file and imported it into Fusion 360.
▼It can be found under the "Insert" menu on the Home tab.


▼I selected the plane where I wanted to add the QR code as a sketch.

▼However, it turned out to be completely different from the QR code I just generated.

Since the original QR code couldn't be correctly imported via the .svg file, I output a .png file from the site, converted that to an .svg file, and then imported it into Fusion 360.
▼I used this page for the conversion:
https://www.freeconvert.com/ja/png-to-svg
▼The QR code was successfully imported as a sketch.


In this state, I could select parts of it just like a normal sketch.
▼I was able to extrude it using the Extrude tool.


▼Since the number of bodies increased and became difficult to manage, I grouped them into a single component.

I adjusted the positions of the QR code and the Haniwa, then added an offset plane and split the model to ensure the base was flat.
▼After splitting, I projected the shape of the bottom edge onto a sketch plane, applied an offset, and extruded it.



PrusaSlicer Settings
▼I am using the Prusa MK4 3D printer.
▼The Prusa MK 4 seems to be out of stock, but the MK4S appears to be available.
For this print, I set it up to change colors between the QR code layer and the Haniwa layer.
▼Information on color changes in PrusaSlicer can be found here:
https://help.prusa3d.com/article/color-change_1687
▼By clicking the "+" button on the right-side scroll bar at the layer where you want to change colors, you can set the printer to switch filaments from that point.

▼The original size was too small and the QR code likely would have blurred, so I scaled it up.

▼Tree-style supports seemed like a good choice.

3D Printing the Output
For the filament, I used some leftover white and black PLA Plus.
First, I tried printing with the coarsest setting, "0.2mm SPEED," with white for the lower layers and black for the upper layers.
The output pauses at the designated color-change layer, allowing you to swap the filament.
▼It changes to black halfway through.


▼This is the final result.


▼The QR code part was too coarse, and the camera couldn't read it.

For the second attempt, I adjusted the settings so the QR code area would bridge without supports, setting only "Enforced Supports." I printed this using the finest setting, "0.1mm FAST DETAIL."
▼The state when swapping the filament. Looking good.

▼This is the finished product.

▼I was actually able to scan it with my smartphone camera!

Finally
I was worried because some of the filament had been left out for about a year and might have absorbed moisture, but it printed without any major issues.
After several adjustments, I was able to print with "0.15mm SPEED" settings, using a single wall and no supports. This reduced the printing time from 2 hours per piece to just 1 hour.
I'm thinking of mass-producing these Haniwa figures to give away as presents at events. I can see myself using this method to combine other figures with QR codes in the future.




