The Making of the 2024 Tempus 3D Holiday Ornament

The holiday season is a fantastic time for making something creative! This year I wanted to make something fun, but also really accentuate the amazing power and capabilities of our our HP Multi-Jet Fusion 3D printer. This printer is capable of printing extremely complex geometries without the need for supports, resolving fine details, and being made from durable PA-12 Nylon material. Looks like I have a fun challenge ahead, and let’s make this a Tempus 3D tradition in the future!

We thought we should share the process of designing the bauble in a short Instructable, and maybe inspire some of you to pick up 3D design!

3D CAD of choice, I'll be using Fusion of course!

Sometimes the most striking effects come from the simplest designs! Of course, this is usually easier said than done. A trick that I’ve learned in designing, is that it’s always better to start off simple, and then add complexity layer-by-layer (pun intended). This allows us to keep the scope of the project manageable and can help with the problem of over designing. So how simple should we start from? The Tree Bauble, a simple recognizable traditional shape!

The key objective for our holiday project was to take advantage of the capabilities of our HP MJF printer. A simple ball would be no challenge at all! To start, let's identify the key strengths of Multi-Jet Fusion Printing.

Benefits of Multi-Jet Fusion Printing

1: No supports needed

More common forms of 3D printing, such as FDM or Resin based printing, usually require supports to be created. Since additive manufacturing is done layer-by-layer and can’t print in empty space, supports act like scaffolding that hold the overhangs in place until the print is completed. With Multi-Jet Fusion (and SLS) printers however, a full layer of powder is always put down on very layer. The machine then binds only what it needs to leaving the unbound powder in place to act as a support. The unbound powder is then removed and reused! This is what allows complicated tight geometry that would be otherwise impossible to make, and as a bonus, there are no artifacts left behind from where supports would attach.

2: Strength:

Our in-house HP PA-12 Nylon is incredibly robust, and as a very important differentiator, MJF printing specifically excels in very consistent strength on all axis! More common forms of 3D printing tend to have a weakness between layers. The material might be strong, but the adhesion between layers could be weak. This could result in breakage. MJF printing’s material strength, and minimal axis strength difference can allow for surprising possibilities, which in this specific case, I want to showcase using uncommonly thin features without fear of layer seperation.

3: Dimensional accuracy and detail:

MJF printing has a high-level of dimensional accuracy, combined with a surprising level of detail. MJF printing is at the very top of combining strength and detail!

4: Adding complexity doesn’t add cost:

While complexity in some cases can indeed make things difficult to print and post-process, generally it doesn’t actually matter! 3D printing is specifically known for its ability to make things that no other way of manufacturing can do, and once you combine it with the no supports needed stated above, the limits are through the stratosphere!

Given the strengths of MJF, let’s develop a plan to implement them!

My idea was to start with a simple sphere and place the Tempus 3D logo right in the middle—a feat difficult to achieve with any other manufacturing technique. I began with a 2D sketch of the basic shape. Since the design is a hollow sphere, I decided that using a 2D profile with the revolve tool would be the easiest way to achieve the desired shape. In this case, I decided to put almost all the features into a single sketch, you’ll see why later.

I opted for a 3-inch diameter with a slim 2.75mm thickness for the outer profile. You can also see the logo plaque here. Note that I didn’t constrain the plaque size because I wanted the flexibility to adjust it later in the modeling process. After adding a simple top hanger, it was time for the first 3D operation!

The first operation was straightforward: creating the outer hollow sphere. I used the revolve tool by selecting half of the outer profile and rotating it about the central axis.

Now that we have our sphere, it’s time to get creative! I started by creating a new sketch a few millimeters from the surface using an offset plane. This sketch defines the intricate “ribs” of the bauble. Rather than drawing the ribs directly, I sketched the areas to be removed, leaving the ribs behind.

As you can see, the blue lines indicate that the sketch is unconstrained. This was intentional—since the design is entirely flexible, an unconstrained sketch allowed me to adjust the lines until I achieved the desired look. I continued playing with these lines throughout the process, making it easy to perfect the design.

Once I was close to the desired shape, I used the extrude tool to cut the design out of the sphere.

Now that I had a single cut, how could I transform it into the intricate final shape? This is where the magic happens—the circular pattern tool. I selected “Feature” as the Object Type, which allowed me to pattern the extruded cut (highlighted at the bottom of the screen). Next, I chose the axis around which to pattern the feature and experimented with the number of repetitions, eventually settling on 20.

The result is quite dramatic, despite the simplicity of the procedure!

Now that we have our bauble, it’s time to add the logo plate and hanger loop. Fortunately, the necessary sketch was already prepared. Let’s start with the logo plate. I used a symmetrical extrude to ensure that the plate remained centered on the bauble. To add our logo, I imported a vector outline of our Tempus 3D logo, created a new sketch on the plate, and positioned it appropriately before performing a simple extrude. In this case, I extruded 1mm to make it easier to see through the ribs.

Next is the hanger loop—a simple square with carefully considered dimensions. Again, I used the symmetrical extrusion tool to ensure it was perfectly centered.

Why dedicate a separate step to adding fillets? There’s a common saying: “The fillet tool is the most expensive tool in CAD.” This isn’t because it’s difficult to use, but because each additional fillet can increase production costs—whether through extra CNC machining time or by complicating injection molds. Fortunately, this ties directly into the fourth benefit of MJF mentioned above. In our case, adding fillets has no impact on the printability of the bauble. So, feel free to fillet away!

I hope you enjoyed this write-up, and that some of you are inspired to try CAD if you haven’t already. This was a fun little in-house project!