This is a 3D model of a keychain, modelled in the style of the IndiaFOSS 2024 conference logo. IndiaFOSS is India's premier volunteer led open source conference, organized by the FOSS United community.
Every year brings in a new logo. Thus, every year I need a new design. The perfect opportunity to experiment and have fun.
I picked up the IndiaFOSS 2024 logo and got to work. I had a good feeling about the logo. It looked fresh. I directly mapped this to the front face - just follow the design. No brainer, really.
What about the back ? I typically design in something on the back side. This is what prints in contact with the heated bed. The bed on my printer has some issues. First layer is never as perfect as I need. The design carefully distracts the casual (non-expert) observer from any imperfection of the print bed.
I settled on the obvious "United By" tagline for the back. A test print with protruding text showed a lot of ugliness printing overhangs. I quickly settled on emboss.
The logo lent itself to a good play of colors. Three colors were used in every keychain, with the following themes:
- Classic - light green, black and white
- India - Orange, Green and White
- Elegant - Pink, Purple and White
- Striking - Orange, Blue and White (Orange and Blue are complementary colors)
- Bengaluru - Yellow, Red and White
Inkscape was used. I found that the logo designer had actually stretched the font to build the front text. Followed the same aspect ratio for the text on the back - "UNITED BY". 2024 on the back is just a flipped mirror copy. All the shapes are simplified. See keychain-elements.svg.
The SVG file is then imported into FreeCAD. FreeCAD doesn't handle shapes with holes correctly. Boolean difference is used to manually fix letters with holes - e.g. "O", "o", "B". These shapes are extruded to build the final model. Thus, the SVG file decides the XY proportions. The model gets its depth in FreeCAD.
A specially modelled shape is used to reduce overhangs to the bare minimum. See the freecad model for details.
After the model was finished, I realized it was too thick. This is a problem both for people to keep in their pockets, as well as it takes a long time to print. Blender to the rescue. Imported the STL, and used mesh editing to reduce the thickness of the front and back faces to 1mm each.
The final STL is in indiafoss-2024-keychain.stl.
I carefully sliced the model with PrusaSlicer, to prepare the model for printing on my Prusa i3 MK2. Used elephant foot compensation. Enabled ironing on all top layers for a great finish. ColorPrint setup to change filament at Z=1.1 and Z=3.2. A 0.25mm nozzle is used to ensure that fine text prints fine. I use ColorFabb nGen, as it has worked great for me for many years. Excellent prints and great colors. The model was scaled by 120% in XY, but Z was unaltered. 3 mm thick keychains is good.
24 pieces of Classic were printed in one go. A 28 hour print. Settings are in mc-indiafoss-2024-keychain.3mf
Here's the printing workflow:
- Initiate the print just before sleeping with the light green filament.
- Wake up in the morning, change to green.
- Change filament at the end of the day to white.
- Wake up to fresh cookies - oops, keychains!
