Over the past few weeks, I’ve been working on a challenging and fascinating design for an impossible 3D object, and I’m excited to share the results! My goal was to create an object that could only be produced through 3D printing due to its unique, impossible nature. After some research, I came across a design for a small ball trapped inside a cube—an object that is impossible to remove without disassembling it or breaking the structure. This is what made it the perfect choice for the project.
As part of the assignment, I needed to use two different 3D printing techniques, and I decided to incorporate both Fused Deposition Modeling (FDM) and Stereolithography (SLA). FDM works by extruding a filament through a heated nozzle, building the object layer by layer, while SLA uses a laser to cure photopolymer resin, creating highly detailed prints. The combination of these two techniques allowed me to explore different printing styles and achieve the level of detail and complexity required for this impossible object.
Because the object had to fit inside the small space of a gumball (roughly 2x2x2 cm), I had to scale down the design significantly while ensuring that the ball would still remain trapped within the cube. This required careful attention to dimensions and an understanding of how each printing method would behave at such a small scale.
I started by downloading the STL file of the design from Thingiverse, then imported it into my slicing software. For the FDM print, I used a Prusa 3D printer, carefully adjusting the settings to ensure the print would be stable and precise. Since the ball needed to remain securely inside the cube during the print, I had to add some custom supports to stabilize the structure. The first print was a bit challenging, but after fine-tuning the settings, I was able to produce the first piece. To speed up the process, I printed two additional copies of the object, streamlining the workflow.
Once the FDM prints were completed, I shifted to the SLA printer to produce a higher-detail version of the object. I imported the STL file into the PreForm slicer software, making sure all settings were adjusted for the resin printer. After slicing, I sent the file to the printer and began the printing process. Once the object was printed, I followed the necessary post-processing steps, including washing the print to remove excess resin and curing it under UV light to harden the material and enhance its strength.
| Cost Type | Cost | Price | Source | Quantity | Total |
| Materials | PLA filament | $0.05/g | Amazon | 30 g | $1.50 |
| Tough 1500 Resin V1 | $199.00/L | MatterHackers | 100 mL | $19.00 | |
| Labor | FDM Printer and SLA printer | $5/h | 3DMaker Engineering | 15h | $75 |
| Curling and drying (SLA) | $5/h | 3DMaker Engineering | 1h | $5 | |
| Prototyping Engineer (You!) | $36/h | Zip recruiter | 1h | $36 | |
| Overhead | Facility Cost (Machine Time) | $350/month | Polyprinter | 20h | 15$ |
Total: $151.5
For this project, I have explored the costs associated with two different 3D printing techniques—Fused Deposition Modeling (FDM) and Stereolithography (SLA)—and compared the cost of producing a single piece using each method. Understanding these costs is essential, especially when deciding which technology to use for a particular project, as each process comes with its own set of advantages and challenges.
FDM Cost Analysis
For FDM, the primary costs come from the materials and the machine time required to print the object. In my case, the material cost for 4 pieces was $1.50, which results in a material cost of $0.40 ca per piece. FDM typically uses thermoplastic filaments like PLA or ABS, which are relatively affordable compared to other materials used in 3D printing. The machine time for printing these 4 objects amounted to $18, which breaks down to $4.5 per piece.
This makes FDM an economical choice, particularly when producing larger quantities or when cost-efficiency is a priority. FDM’s relatively low machine and material costs are one of the reasons it is a popular choice for prototyping and creating functional parts.
SLA Cost Analysis
In contrast, SLA printing involves different costs, primarily driven by the higher price of resin material, as well as the time required for both the printing and post-processing stages. For this project, the material cost for printing 1 piece using SLA was $10 ca. SLA uses a photopolymer resin, which is more expensive than the thermoplastic filaments used in FDM printing.
In addition to the material cost, SLA also involves higher machine time costs. Moreover, SLA prints require extensive post-processing, including curing and washing, to ensure that the printed object achieves its final strength and finish. The cost for curing and post-processing came to $5 for washing and for curing, amounting to $15 per piece.
Overall, the project was both rewarding and challenging. It required a good understanding of 3D printing techniques and how different materials behave at small scales. In the end, I was able to create an impossible object that would not have been possible to fabricate using traditional methods, showcasing the unique power of 3D printing.
