Molding and casting have been fascinating to me all life long. From a very young age, I always made my hand mold with sand and water whenever I was at the beach. I used alginate to make a mold for my middle finger as hooks. With the alginate mold ready, I poured in plaster of Paris to cast my spooky finger hook.

how to be a master chef in making alginate mold to cast finger hook

1. make the alginate mold

I mixed the alginate and water in a 1:1 ratio. I tried to be as accurate as possible in getting the correct ratio, as it will take longer for the finger mold to cure if too much water is present. I inserted my middle finger into the alginate mold when it was close to the alginate mold pot time of 5 minutes. Then, I waited another 5 minutes to ensure the mold cured and solidified to the contour of my middle finger. I took extra caution in taking out my finger from the mold as fast and careless finger removal may break the mold.

2. time to cast my finger with plaster of paris

I prepped the plaster of Paris with water in a 2:1 ratio. I mixed the plaster for 3 minutes before pouring the plaster mixture into the alginate finger mold I made earlier. Furthermore, I attached a screw to the end of the plaster I had just poured in to make it function as a finger hook. I secured the tip of the screw with paper tape on a popsicle stick to have only the tip of the screw exposed.

3. fun time to check my finger cast and de-mold it

For my first finger cast, I came back to OEDK to de-mold it after leaving it in the mold overnight. I was surprised about the turnout of my finger. It even had the details of my nail and lines on my skin. The only failure of my finger mold was that I inserted my finger too deep during the molding process. I got a cast result of a flat surface on the top of my finger. To proceed with making the second identical finger cast, I mixed the plaster of Paris and water with the same 2:1 ratio and poured it into the same alginate mold I used for the first finger cast.

4. post-process my finger cast with sandpaper

After taking out the second finger cast, I could proceed to the post-process phase of making the finger cast hook. I used 80-grit sandpaper to grind down the imperfections caused during the molding and casting process.

5. Time to add some color theme to the finger by spraypainting

I used the RUST-OLEUM 2X UltraCover Paint+Primer to spray paint and cover my finger casts with the grape color paint. 2 more light coats were applied 3 minutes apart before moving to RUST-OLEUM Gloss Clear Coat. I applied 3 layers of light Gloss Clear Coat 3 minutes apart.

6. back to more spraypainting and clear coat afterwards

After completing 3 layers of grape spray paint and 3 layers of gloss clear coat, I found the grape color on my plaster fingers lighter than I expected. I went on to repeat steps as mentioned in step 5 to try to achieve a darker purple hue. The end result turned out that I needed more light coats on the material that had porous surfaces.

7. time to harvest my plaster finger hooks after drying out

I waited 1 hour before coming back to OEDK to call it a day and complete the finish of my finger casts.

8. clean up the workspace

I made sure to put back all the spray paint and clear coat bottles that I used to make my spooky fingers. The cleaniness of the workplace is the collective responsibility of everyone who is using the space as our privilege.

Reflection after completion

Overall, I enjoyed the process of officially making my first finger molding and casting. I will keep the spooky fingers for my Halloween decorations next year. Now, I am better equipped with the knowledge and experience as an engineer aspiring to work in the medical device field. Molding and casting will be essential skillset in my arsenal to make something cool in the future.

Four major takeaways for the future molding and casting work:

1. Make the finger alginate mold better without bottoming out my finger during the molding process
2. Make a second finger mold for casting the second plaster finger to achieve the goal of making two identical pieces better as the alginate mold shrinks over time due to water evaporation
3. Sand the surface with fine-grit sandpaper to remove loose particles and create a rough texture for better paint adherence on porous material
4. Choose spray paints for porous surfaces, such as enamel-based sprays, which are available at OEDK

manufacturing cost analysis

The overall cost of manufacturing my two plaster finger casts is $ 58.35. The biggest part of the manufacturing cost came from labor, including the molding/casting operator and prototyping engineer, and overhead. If we scale up the manufacturing of finger casts, the upfront cost could be divided by a greater number of pieces manufactured, resulting in a lower price per piece.

Cost Type	Cost	Price	Source	Quantity	Total
Materials	Alginate Molding	$ 19.99	amazon.com	10% bag	$ 1.99
	Plaster of Paris	$ 17.29	amazon.com	1.37% bucket	$ 0.24
	Screw	$ 5.49	amazon.com	0.8% pack	$ 0.05
	Popsicle Stick	$ 4.99	amazon.com	1% pack	$ 0.05
	Paper Tape	$ 7.99	amazon.com	0.25% roll	$ 0.02
	80-Grit Sandpaper	$ 3.99	amazon.com	0.8%	$ 0.03
	Rust-Oleum Painter’s Touch 2X UltraCover Paint+Primer (Grape)	$ 6.48	homedepot.com	1.67% bottle	$ 0.11
	Rust-Oleum Painter’s Touch 2X UltraCover Matte Clear	$ 6.48	homedepot.com	1.67% bottle	$ 0.11
Labor	Molding/Casting Operator	$ 19/hr	ZipRecruiter.com	0.5 hr	$ 9.5
	Prototyping Engineer (You!)	$ 25/hr	Indeed.com (Engineering Intern)	0.5 hr	$ 12.5
Overhead	Facility Cost	$ 20/hr	MakerSpace Membership Hourly Cost	0.5 hr	$ 10
	Quality Control	$ 22.5/hr	Glassdoor.com (Quality Assurance Inspector)	0.5 hr	$ 11.25
Design	Engineering and Development	$ 25/hr	Indeed.com (Engineering Intern)	0.5 hr	$ 12.5

Total Cost: $ 58.35