To create a print that could only be made using 3D printing, I used the website thingiverse. I searched impossible geometries on the website and quickly found an ornament geometry that seemed like it would be fun to print.

 

I imported the design onto Bambu studio and scaled the file to fit into the gumball machine, used the auto-generated normal supports, and hit print.

When it was finished, I quickly realized that the print was overloaded with supports, and the intricate inner geometries had poor resolution. In attempting to remove the supports, I broke my part. I went back to the file and tried minimal tree supports instead. This was better, but I broke the part when removing the supports, and the geometries still had bad resolution. I decided at this point that scaling the file down to fit in the gumball jar (60% of the original file) made this design come out with poor resolution and was hard to support with its large amounts of overhangs.

 

I returned to thingiverse and found a file with interlocked cubes by user: Bastien.

This design could be scaled down and allowed for access to remove supports after printing. I scaled the file down to 75% of the user’s specifications. This created a print with 37.12 x 26.94 x 36.44 mm which fit well into the gumball jar (48.7 mm radius and 38.7 mm height).

I printed 3 copies of the cubes on the Bambu FDM printers with tree supports.

I then switched over to SLA printing using the Formlabs printers and made 2 more sets of interlocking cubes. I ensured that the scale was the same and then generated supports. After printing, I washed and cured the design before removing the supports.

I am happy with how the final prints turned out! I cleaned up the mess made from cutting supports after each print.

Cost Table:

Cost Type	Cost	Price	Source	Quantity	Total
Materials	White PLA Filament	$14.99/kg	Amazon.com	0.11	$1.65
	Tough 1500 Resin	$149/L	Formlabs.com	0.6	$8.94
Labor	3D Printer Operator	$21.47/hr	Ziprecruiter.com	1/4	$5.37
Overhead	Facility Cost (Machine Time)	$0.10/hr	Slashplan.com	18	$1.80
	Quality Control	$13.00/hr	Zippia.com	1/2	$6.50
Design	Engineering and Development	$35/hr	Red Fox Innovations	1/4	$8.75
	CAD Software (Fusion 360)	$545/year	Autodesk.com	1	$1.49
Misc.	Waste and Scrap	$13.50/hr	Ziprecruiter.com	1/6	$2.25
Total					$36.75

Cost Analysis:

I calculated the weight of PLA prints to be 54.66 grams (1 gram per cubic centimeter of PLA, 3.7 cm * 2.7 cm * 3.6 cm (size of print) = 36.44 grams * 0.5 opacity factor = 18.22 grams * 3 PLA prints = 54.66 grams. Then adding my 3 failed prints you get a total of around 109.32 grams which is 11% of the kg roll I found on amazon. Online (Phrozen technology) it states that the average small figurine SLA prints use around 20-50 mL per print so accounting for 2 prints and using 30 mL/print we get an 60 mL print or 6% of the liter tank. As the 3D printing operator is a fairly quick task I estimated the operator would spend 15 minutes adding supports, slicing the files, and sending it off to the printer for all 5 prints. For overhead on facility cost, I added up the time for all my prints (and failed prints), washing, and curing and estimated 18 hours of machine time. For quality control, I used this as the time to take off supports and inspect the quality of the print and estimated half an hour. The engineering of the files themselves would not be very labor intensive as the design only features two hollow cubes which could be made very easily by an experienced CAD user in ¼ hour (using a fusion360 software subscription). This was a very easy project to clean up the waste for so I estimated only 10 minutes of clean up time. The total cost I estimated was $36.75 which was the cheapest cost so far for the assignments in this class showing the cost-friendly utility of prototyping using 3D printing methods.