Introduction

I decided to go with the Intermediate choice for my 3D printing project because I have a little previous experience with 3D printing, specifically with the Prusa i3 mk3 printers. I chose my impossible object to be an Impossible 2D cube, made by hailodiver, which I downloaded from Thingiverse after searching for a decent amount of time. As I was scrolling through Thingiverse, this impossible object caught my eye as I have always liked to sketch 3D cubes on papers during class while I was bored. And now I can print an exact copy of my hundreds of sketches.

Print type 1: Prusa i3 mk3 (FFF)

I printed four of my five objects using the Prusa i3 mk3. I first downloaded the .stl file off my impossible object and then opened the file with 3DPrinterOS. I first printed 4 cubes (all within the same file) of the original size as I thought it might fit within the gumball capsule. I then scaled down it down to 70% of its original size and it fit within the capsule a lot better.

I then printed 4 cubes at 70% of the original size (all within the same file) in two different colors to get some variety, to make sure that my print was successful more than once, and to have some extra cubes to keep for myself. No supports or build plate adhesion was necessary as my impossible object is very short in height. I increased the layer height slightly as I thought the cubes would look cooler if the layers were more defined. I used PLA filament for all of my Prusa FFF prints.

All my 70% scaled prints were a success! I selected two white colored cubes and two green colored cubes to place in the gumball capsules.

Print type 2: Prusa SL1S (SLA)

I printed the fifth of my five objects using the Prusa SL1S SLA printer. I used the same .stl file but opened it in a different slicing application, one that was specific to the Prusa SL1S. I then sliced the file using the same dimensions, found using 3DPrinterOS, as the 70% scaled prints from before. Again, as my cube was very short in height, I didn’t need to print with any supports or pad.

As I have never used this printer before, I read the manual before using it. I also received help from a lab assistant that knew how to set up the printer to make sure I wasn’t forgetting anything. As I was only printing one cube, the print time was very short, a little longer than 5 minutes. I then removed the printed cube from the printer. I took my time using the spatula tool to remove my printed cube from the printer as due to the thin quality of my print I didn’t want it to break as it was being removed. I then put my print in the washer for 10 minutes. The only error was the small mess I made, but I took the time to clean it all up.

My print came out as a success!

Cost Analysis and Calculations

Prusa i3 mk3 (FFF):

• Raw Materials Cost – One print of 4 cubes that used 10.05g of PLA for $0.20. Two prints of 4 cubes that used 3.35g of PLA for $0.07 each. Total material cost = 0.20+0.07+0.07=0.34. Total materials cost was $0.34.
• Machine Cost – One print of 2hr 12min, two prints of 39min for a total machining time of 5hr 3min
• Labor Cost – No help from lab assistants, so $0 worth of assisted help labor. I took 10 minutes to slice and print, and 5 minutes to process. At $10/hour, labor cost was $2.50 for my 15 minutes of labor.

Total Cost for Prusa i3 mk3 (FFF) prints was $2.84.

Prusa SL1S (SLA):

• Raw Materials Cost – One print of one cube that used 3.59ml of default orange resin. As cost of orange resin is $80/1000ml, Raw materials cost = (3.59ml * $80/1000ml). Total cost of raw materials for this print was $0.29.
• Machine Cost – One print of 6min 49sec.
• Labor Cost – Help from lab assistant for 15 minutes. At $10/hour, labor cost for lab assistant assistance was $2.50.  I took 10 minutes to slice and print, 10 minutes to process, and 10 minutes to clean up for a total of 30 minutes of labor. At $10/hour, labor cost was $5.00 for my labor. Total labor cost for this print was $7.50.

Total Cost for Prus SL1S (SLA) print was $7.79.

Cost for this project overall was (7.79+2.84) $10.63.

Conclusion

Even though I had experience using 3D printers before, this was the first time that I went through the entire process of using the Prusa i3 mk3 printers by myself. I gained confidence in my ability to use the printers. I also enjoyed learning how to use the Prusa SL1S and hope to use it more in the future (and with less of a mess).

One thing I would change with how I approached the project is choosing a taller object. I only realized very recently, that my choice of object, even if I thought it was cool, didn’t give me a lot of opportunity to learn, such as with using supports, which is an integral part of 3D printing.

Moving forward, I want to continue using 3D printers, trying to print more difficult prints that need supports and take longer to print. I may even pick a different, taller impossible object to print outside of class. I want to feel very comfortable printing pretty much anything I would need for a design project for class or for a club, and I’m happy that this project gave me a really good start towards that goal.