Assignments:

My task for this week are:

• Model (raster, vector, 2D, 3D, render, animate, simulate, …) a possible final project, compress your images and videos, and post a description with your design files on your class page

Helpful Notes:

• Try experimenting with different 2D and 3D design tools (e.g. Fusion 360, Rhino, FreeCAD, Illustrator, Inkscape, Blender).

• Focus on designing components relevant to your final project rather than random models — this helps build early progress.

• Use parametric design tools to make your models easily adjustable later.

• Document both process and result — include screenshots, sketches, and iterations.

• Clearly explain the purpose and relation of each design to your final project idea.

Checklist:

• Modelled experimental objects/part of a possible project in 2D and 3D software

• Shown how you did it with words/images/screenshots

• Documented how you compressed your image and video files

• Included your original design files

From Zero to Hero: Introduction to 3D CAD

Before starting this project, I had no prior experience with 3D CAD. I had heard terms like sketch, extrude, and solid modeling before, but I didn’t really understand how they fit together or how people actually design real products using CAD software. At first, 3D modeling felt intimidating, because everything looked technical and precise, and I assumed you had to “think like an engineer” from day one.

What I learned very quickly, though, is that 3D CAD is not about drawing objects directly, but about building them step by step using simple operations. Almost every 3D model starts from very basic shapes, and complexity is added gradually. Once I understood this mindset, CAD started to feel much more approachable.

The general idea behind 3D CAD:

In most CAD programs, the workflow follows a clear logic:

1. You start in 2D

2. You turn that 2D sketch into 3D

3. You modify the 3D shape

4. You refine it so it can actually be manufactured

Instead of freely sculpting shapes, CAD tools rely on constraints, dimensions, and parameters. This means that shapes are defined mathematically, not visually. While this feels restrictive at first, it actually makes designs much more reliable and editable later on.

Bringing the Smart Coaster to Life

When I first started this project, I was a total newbie to the world of 3D modeling. I had this vision in my head (and on paper!) of a coaster that didn’t just sit there, but it needed to be a personal health assistant that could heat my coffee, show of my consumption via app, and track every sip I took, so that it can give future recommendations. But turning that into a digital 3D model was a massive learning curve. I had to go from “What is a sketch?” to “How do I fit a heating plant and a scale into a 110mm circle?”

1. The Top Plate (The Ultimate Dual-Tasker)

The trickiest part of the whole design was the top plate. In my CAD program, I had to design this 90mm center disk to do two things at once, which felt almost impossible at first.

• The Weight Logic: Instead of just a simple lid, I designed the top surface to act as the primary interface for a digital weight sensor. This was a huge learning moment for me in Fusion 360. I had to ensure the top plate was positioned so that when you set a cup down, the pressure travels directly to the internal sensor. It’s essentially a smart “lid” that tells the coaster exactly how much you’ve been drinking.

• The Heat Logic: This same surface is also where the heat pads live. I had to figure out how to mount the thermal pads right under this top plate so that heat (for my coffee) or cold (for my water) transfers efficiently. So, I need to design a part that is sensitive enough to weigh a few grams of water but tough enough to handle high temperatures.

2. Breathing Room (Thermal Vents)

• The Design: I couldn’t make the coaster a solid, airtight puck. If I did, the electronics would fry! I need to learn how to cut ventilation slots into the “neck (the middle)” of the coaster. These allow the internal fan to pull in air and exhaust the waste heat.

• I could also add a small fan inside for ventilation purposes, and it could be also used as to cool the top plate, which would help to both stabilize the temperature. Once this is done, it could also be used to cool the drink with colder top plate.

3. Physical Controls (The Human Touch)

Even though the coaster connects to an app, I wanted it to be useful on its own.

• The Buttons: Temperature Increase, Decrease, and my personal favorite, the Do Not Disturb (DND) button.

• The Light Ring: I will add a translucent ring around the middle of the design. This acts as a “light pipe” for the RGB Reminder Light. It’s the visual heart of the coaster—glowing to remind me to hydrate or changing color when my drink hits the perfect temperature.

4. The Internal

The final phase of my CAD work was what I call “Internal Tetris.” I had to make sure every single component had a “home” inside the 110mm diameter housing. My model is a vertical stack of layers:

• Bottom Floor: The battery and the ESP32 “brain.”

• The Cooling Center: The fan and the heat sink.

• The Sensor Deck: The digital scale’s load cell.

• The Top Floor: The thermal pad and the scale’s surface.

Now that we made up some ideas, we can move to our initial building step, the sketch.

Sketching: the foundation of everything

Every CAD model starts with a sketch.

A sketch is a 2D drawing made on a plane (for example: top, front, or side).

At the sketch stage, I’m not thinking about thickness or height yet. I’m only defining:

• circles

• rectangles

• lines

• arcs

The key thing I learned is that sketches should be:

• fully constrained (nothing can accidentally move)

• dimensioned (sizes are clearly defined)

Even something as simple as a circle becomes powerful when it has an exact diameter and is locked to the center.

From 2D to 3D: extruding and cutting:

FreeCAD

!I haven’t included the top design, as it is nearly same as the bottom one!

Once a sketch is finished, it can be turned into a 3D object using operations like:

• Extrude → gives thickness to a shape

• Cut → removes material from an existing body

This was a big “aha” moment for me.

Instead of drawing a 3D object directly, I learned that I should think in terms of:

“What shape do I want to add?” “What shape do I want to remove?”

By stacking these operations, complex objects slowly emerge from very simple beginnings.

Thinking in parts, not just shapes

As I became more comfortable, I started to realize that CAD is not just about making things “look right”, but about designing real parts that fit together.

This means thinking about:

• wall thickness

• clearances

• how parts are assembled

• where electronics will go

• how heat, screws, or wires move through the object

This mindset shift was especially important for my final project.

Because in order to do this, I have changed my path to Fusion 360 to build an initial draft

How I approach the Smart Coaster in Fusion 360

Instead of trying to design everything at once, I approach the Smart Coaster step by step:

• Start with the outer shape

• Define the overall size

• Leave the top plate empty for now

• Hollow the body

• Prepare internal space for components

• Refine edges and surfaces

This way, I can always go back and adjust dimensions without breaking the entire model.

Smart Coaster Fusion 360 Design Process

1. Sketching the Foundation: I started by creating a 2D sketch on the ground plane, using concentric circles to define the footprint and the wall thickness of the coaster.

2. Creating the Base: I used the Extrude tool to pull the outer profile upward, creating the solid cylindrical base that forms the main body.

3. Hollowing the Core: To make room for the cup and internal electronics, I performed a secondary extrusion to “cut” the center out, leaving a sturdy outer rim.

4. Designing the Internal Lip: I added a specific offset extrusion inside the cylinder to create a shoulder. This acts as a mounting point where I can eventually seat a top plate or a sensor.

5. Refining the Geometry: I applied Fillets and Chamfers to the edges to smooth out the transition between the walls and the base, making it look more like a finished consumer product.

6. Component Comparison: I duplicated the body and moved it to the side so I could iterate on the design while keeping a reference of my original draft right next to it.

7. Finalizing the Profile: I adjusted the heights and diameters of the rings to ensure the “smart” components would have enough clearance without making the coaster too bulky.

Timelapse of the Smart Coaster

Timelapse

Also, another cool overall preview of the design.

Preview

Both thumbnail credits to Gemini

Starting The Grind All Over Again with Fusion 360

Alright, now that I’ve leveled up my CAD skills and gained some real experience, I’m going to pull a ‘reincarnation anime’ move: I’m heading back to the beginning of the grind and restarting the entire design from scratch to achieve the perfect final version of this smart coaster. But, this time I will make it step by step, so that you can follow up in the process. I wanted to do this because after messing with Gemini for my probable design of the final project (like after I sent my initial draft design), it gave out a great result of the final design that I can use. It was also looking great and covering every other feature that I didn’t include before: the buttons, ventilations, USB-C slots, and more… Besides, this designed also matched with what I was expecting of my final project.

Credits to Gemini

PART 1 — MAIN ENCLOSURE BODY

Create new design

• Open Fusion 360

• File → New Design

• Bottom right → Document Settings

• Units → Millimeters (mm)

STEP 1 — Base cylinder (main shape)

1. Create Sketch → select Top plane

2. Draw Center Diameter Circle

3. Set diameter: 110 mm

4. Finish Sketch

5. Extrude

• Distance: 28 mm

• Operation: New Body

This is your main enclosure volume.