PART I: Introduction
In this section, I learned how to use molding and casting to create an object. I plan to apply this skill to my final project by duplicating eight identical chess pieces.
It was my first time working with molding and casting, and I found it fascinating. When I discovered that the main material for molding was alginate, it felt familiar since this hydrogel is commonly used in biomedical research. Similarly, the plaster of Paris used for casting is also used in dental applications. It was amazing to realize that these materials can be applied across different fields.
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PART II: Workflow
- First: Molding
I used 23g alginate to mix with 200 mL water to prepare the hydrogel for modeling. After mixing well, I put my finger into the hydrogel for 10-15 minutes. Once the hydrogel polymerized, I took my finger off from the hydrogel, as photo shown below.
. - Second: Casting
Following the last step, I mold two fingers. I chose the best one for casting. I mixed 50 mL water with 100 units (v/v) of the plaster of Paris (1:2) together and then added it to my mold. For my first casting finger, I put it at room temperature waited for overnight. For the second one, I only waited for 45 minutes. Below are two fingers I cast by using the same mold.
. - Last: Post-processing
Last, I used sandpaper to polish the surface. Also, I attempted to add more detail on my casting fingers. Later, I used spray paint to finish my objects.
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PART III: The Work Space
The space was cleaned after used.
PART IV: Cost Estimation
| Cost Type |
Cost | Price | Source | Quantity | Total |
| Materials | Alginate | $18.79 | Amazon | 1.5 lb | $18.79 |
| Plaster of Paris | $9.85 | Amazon | 8-pound | $9.85 | |
| Sandpaper | $14.98 | Home Depot | 1 pack | $14.98 | |
| Gray Spray Paint | $5.98 | Home Depot | 1 ea | $5.98 | |
| Labor | Prototyping Engineer (You!) |
$25/hr | Indeed.com (Engineering Intern) |
1 hrs | $25.0 |
| Overhead | Quality Control | $22.5/hr | Glassdoor.com | 1 hr | $22.5 |
| Design | Engineering and Development | $25/hr | Indeed.com (Engineering Intern) |
1 hr | $25.0 |
Total: 122.1
The total for completing the molding and casting objects is $ 122.1 for two pieces, which means one piece costs 61.05. Most of the manufacturing cost was raw materials preparation since you have to buy a package at one time. Thus, if I mold and cast more objects in the future, the cost of each piece will decrease significantly.
