For this project, I explored the fascinating process of casting and molding by creating a mold of my fingers and using it to produce plaster replicas. While it seemed straightforward at first, I encountered challenges that tested my problem-solving skills, but in the end, I created a unique set of metallic-finished plaster fingers!

Preparing the Materials                                                                                                                                       

The first step was gathering the necessary materials to create the cast. For this portion, I needed a large cup (to hold the mold), a small cup (for measuring), a scale (for precise measurement), water, alginate, plaster of paris (for step 2), and popsicle sticks (for stirring the mixtures). Alginate is a water-based material, it dries and shrinks quickly, making it a one-time-use material in most cases.

Creating the Mold                                                                                                                                                       

I added 33g of alginate and 125g of water to create the mold. After making the mixture I started stirring quickly before the mixture began to set. Once I had a smooth, lump-free consistency, I carefully submerged my fingers into the mold and held still, waiting for the alginate to solidify. After almost 10 minutes, it transformed into a soft rubbery mold, that captured the shape and texture of my fingers. The tricky part was removing my fingers without damaging the mold, I had to wiggle them out while keeping the structure intact gently.

Casting the Fingers in Plaster                                                                                                                         

With my mold ready, I took the next step into making Plaster of Paris with a ratio of 2:1 plaster to water. After getting the correct consistency, I poured the liquid plaster into the mold. To make my casts functional as hangers, I embedded screws and a jig into the plaster before it set. I left the plaster to solidify for more than 24 hours.

My first attempt was not successful, as the screws were very close to the edge of the cast and they broke. They were not salvageable, so I decided to make another attempt.

Troubleshooting and New Attempts

I repeated the process, however, due to the unpredictable weather and humidity the cast of fingers broke again. After two failed attempts, I decided to take a step back and reconsider my approach.

For my final attempt, I made two key changes:
Controlled Drying Environment: Instead of leaving the mold outside, I placed it inside my box at the OEDK to dry under stable conditions.
Screw Placement: Instead of inserting the screws first, I poured the Plaster of Paris first, then carefully placed the screws while the plaster was still soft.

This time, it worked! Once the plaster was fully set, I carefully peeled away the alginate using a screwdriver. The result? A solid, fully intact cast!

Final Touches

For a final touch, I spray-painted them with a metallic brass color, followed by a clear gloss coat for a polished look. My custom hangers were now done!

This project was both a fun and a learning experience. I learned more about the material properties, environmental factors, and small changes that can impact the design of a cast. Through trial and error, I improved my technique, and in the end, I created a cast.

Cost Analysis

Cost Type	Cost	Price	Source	Quantity	Total
Materials	Alginate	$18.25	amazon.com	1	$18.25
	Plaster of Paris	$9.76	amazon.com	1	$9.76
	Spray Paint  (Metallic brass spray paint, Clear Gloss)	$9.49  $5.98	Spray Paint Clear Gloss	1 each	$9.49  $5.98
	Jigs	$8.99/100pcs	amazon.com	3	$0.27
	Screws	$7.99/150pcs	amazon.com	6	$0.32
	Containers	$10.99	amazon.com	1	$10.99
	Popsticle sticks	$3.99/100pcs	amazon.com	6	$0.24
Labor	Prototyping Engineer (You!)	$36/hr	ziprecruiter	5 hours	$180
Overhead	Facility Cost	$0/hr	Outdoors/Indoors	3 days	$0

 

Total cost: $235.30

Picture of clean station!