This was a project I did at the end of 2023 as a Christmas gift for my brother, and it’s one of the most challenging fabrication projects I’ve ever done. It’s a miniature of the Golden 1 Center in Sacramento (right), which is famous for it’s massive purple laser that shoots into the sky whenever the Sacramento Kings basketball team wins a game. I had the idea to create a miniature beam effect by shining a laser up through a plume of water vapor, and my brother is a massive Kings fan so I decided to build it for him.
Here’s a breakdown of the steps that went into building it:
-3D modelling the Golden 1 Center with room for all internal components
-3D printing the model
-Creating the illuminated letters on the front
-Creating a plume of water vapor
-Shining a laser into the water vapor
Before I started any modeling I made a visit to the Golden 1 Center in person and took reference photos all the way around. The stadium, shown on the right here, is a very unusual shape; roughly octagonal with a rectangular portion extending out of the back. I made some fairly substantial changes to the shape of it, simplifying parts, changing up the proportions, and making it symmetrical. My focus was really capturing the look of it from the front, and adapting the rest to fit. These changes made it much easier to model and build, and also gave it a bit of a stylized cartoony look, perfect for a miniature.
Creating the 3D model of the stadium was a big task and I used a combination of Autodesk Fusion and Maya. Fusion was for the precise and complex main structure of the model that would house all the components, and Maya was for the front façade panels with the illuminated lettering. The whole thing could have been done in Fusion, but since I had 15 unique pieces making up the front panels and letters, it was going to be faster and much simpler for me to do them in Maya using vertex modeling.
To the left you can see the Fusion model with a cross section on top and an exploded view on the bottom. The model consists of the main body (pink), the lid (orange), the fan housing (blue), and the power supply housing (green). I created and printed a first version of the model and tried fitting all the components in. It worked okay, but I felt there was enough room for improvement that I redid the entire thing. On the second attempt I was able to make more room for the wiring, fit the parts together more efficiently, and overall build the model more cleanly. The main body has a central chamber for holding water and an atomizer, a front area for LED strips, a slot for a laser pen module, and room all the way around the for the wiring. The lid has some holes for the on/off switch, the water inlet, and the vapor spout. On top of the lid there is a fan housing that fits on top of the water intake. Lastly there is the power supply housing which slots into the back with some side rails to keep it secure. The vapor spout in particular took the most trial and error to get the right shape and direction of the vapor plume. I didn’t get it working quite as perfectly as I wanted, and I wish I had separated it from the lid so I could have made more improvements without reprinting the entire lid each time. This was actually something I did on the first iteration, but I thought I had perfected the spout design and opted not to separate it in the second version.
For the front panels and letters, I brought the fusion mesh into Maya and modeled the individual panels to fit. The panels on the real building have a variety of shapes with different slopes on them, and on top of that I needed to punch letter-shaped holes through most of them. In Maya this was a pretty straight forward process of making a flat base panel with edge loops in place so that I could duplicate it and easily move a few vertices up to create the different slope shapes. After that I created the letters in 3D, moved them into place on the panels, and used a subtractive boolean to punch the holes into the panels. Below you can see the individual panels which would be wrapped around the front of the main structure after printing.
3D printing the models was fairly straight forward. I have plenty of experience with creating models for 3D printing, so it went relatively smoothly. The biggest challenge was time and patience. The model was at the very limits of how large my 3D printer can go, and I slowed the print speed down to minimize printing mistakes or failures. This meant the main body was a 48 hour print, plus another 24 hours or so for all the rest of the parts. To the right here you can see the main body freshly printed.
One very big problem to figure out was waterproofing. The central chamber has to hold water, and PLA prints are generally not watertight. It is possible to make a watertight PLA print, but it’s a very finnicky process and I had to be extra careful since the water sits just over the power supply. I discovered a product called conformal silicone coating, which is typically used to put a protective coating over circuit boards for electrical insulation and preventing water damage. It comes in a small bottle with a brush built into the lid like fingernail paint. I gave the inside of the chamber a few coatings. The coating fluoresces under UV light, so I used a UV flashlight to make sure I was getting thorough coverage. This ended up working perfectly and I was able to hold water in the chamber for 48 hours with no signs of leakage.
The model also had to be somewhat airtight since I would be using air pressure to create the vapor plume. I added the coating to the underside of the lid to prevent water vapor from seeping into the plastic. I had also designed the top edge of the water chamber with a channel cut into the top surface all the way around the chamber. The idea with this was to take a strip of flexible TPU printer filament and insert it into the channel. The geometry of the channel would let the TPU filament protrude slightly above the surface and act like a gasket between the lid and the main body. This didn’t work as well as I had hoped, so instead I used a layer of silicone around the top edge of the chamber. I set the print upside-down on some wax paper and let it dry. This created a nice flat silicone gasket and worked way better than the TPU strip idea. You can see the waterproof coating inside the chamber and the silicone gasket on the left.
The illuminated letters on the front was a two-part process: an LED strip on the inside, and a way for that light to shine through the lettering on the front panels. I used some standard 5v addressable LED strip and an Arduino Nano- my standard setup for lighting projects. The led strip lights up purple with a little bit of flickering color variation to it. For the front panels, I laid them face-down on some wax paper and filled the letter-shaped holes with a transparent purple epoxy. This was a little messy and needed some sanding afterwards but worked pretty well. After that I tried to cover the entire front of each panel with a silver spray paint so that the letters were hidden behind the paint when turned off. This didn’t work well at all because the silver paint even with a very thin layer blocked almost all the light from coming through when it was turned on. Instead I ended up cutting out masking tape to precisely cover the epoxy letters, then apply the silver spray paint. After that I took off the masking tape and gave each panel a thin finishing coat of epoxy. This process took a lot of experimenting, sanding, and re-trying. I was hoping to get a very smooth satin silver finish, but with the complications of the epoxy and time running short I ended up with a more glossy look. It still came out decently though. To the upper right you can see the final product in the light, and the glowing letters below that.
Finally there was the main attraction- the beam itself. The actual beam on the Golden 1 Center is an 1,800 watt laser display array, so it has no trouble brightly illuminating the atmosphere. For my miniature beam, I used a laser module out of a cat toy rated at “less than 0.39 milliwatt”. This makes for a laser beam that is basically invisible under normal conditions, and any laser bright enough to be visible in the air is powerful enough to cause some damage. What we have to do is shine the laser through tiny particles suspended in the air, which will scatter the laser light and create a visible beam. If you’ve ever used a low power laser pointer in the dark, you may have been able to very faintly see the beam of the laser because of dust particles in the air. Laser shows at concerts get visible beams by filling the air with glycerin fog. I opted to use water vapor because water atomizers are small and inexpensive, and it means the device can be filled with water from the sink instead of buying fog effect fluid.
Down below I have a diagram of how the laser and water atomizer work together. The fan housing on top of the lid is secured with magnets, so it can be removed and the chamber can be filled with water. The atomizer sits at the bottom of the chamber and uses ultrasonic frequencies to create water vapor. When it is turned on, this vapor rises up out of the water and fills the top of the chamber while the fan blows air down into the chamber at the same time. This creates positive pressure in the chamber, which is forced out of the spout on the lid. The laser module sits just underneath the spout and the laser beam comes up through a second hole right next to it. The vapor creates a vertical plume with the laser shining right up through it, resulting in a visible beam. As an added bonus, the water vapor byproduct means it is effectively a humidifier, perfect for the dry Sacramento weather.
This was a very complicated project all the way through and there are tons more small details in the design and building process I’ve skipped over. It took about 2 months of continuous work and a combination of a bunch of my skills and knowledge- 3D modeling, CAD, 3D printing, electronic circuitry, programming, fluid dynamics, physics, and the general engineering experience you get from building things in general. As with any project, there are plenty of things I would improve on if I were to do it over again, but overall I’m very happy with it. And most importantly, my brother absolutely loved it, even if I was a few days late finishing it up.