This week, our assignment was to create 2 casts of our fingers.

Procedure:

I started off by mixing alginate and water at a 1:4 ratio by mass (50 g alginate and 200 g water). This was mixed until it has a cake batter-like consistency and then I inserted my index finger in the form of a hook. This took a pretty short time to solidify – maybe a minute or so. My finger then slid right out and I had a mold of my finger hook 😊

The next thing I did was mix plaster of paris with water at a 2:1 ratio by volume using a volume measurement container. This was more watery than I was expecting, and then I poured it into the mold. I also placed a screw at the end of the plaster to make it a wall hook (and facilitate removal from the mold). This took about 30 minutes to harden.

When I came back, it was very easy to slide out of the mold, and I had my first finger cast done.

I repeated the plaster process again, but when I was going to take the cast out of the mold, the screw came apart from the cast. I thought that if I could get the screw to stick to the cast, I could pull it out and then repour the plaster. Unfortunately, when I did this, the glue stuck the cast to the mold so I had to start over🤦‍♀️

This was a quick process though and I was able to redo it over the weekend.

One thing I did notice was that although I made multiple casts, each one seemed a little different than the others. Some had more bubbles, some had more defined creases, and some even seemed to be thinner than others. I think this may have been due to the mold drying out over the days that I used it and also the pouring technique that I used.

I ended by sanding the pieces (especially the nail that was a bit more fragile and prone to breaking), and then spraying them with a clear coat.

Cost Analysis:

Raw material cost

Material	Ticket Price	Spent
Alginate	$8.99/lb.	$1.98 (100 g)
Plaster of Paris	$22.78/25 lbs.	$0.40 (200 g)
Clear spray paint	$6.98/bottle	$3.49 (overestimate)
Total		$5.87

Labor cost

Assuming minimum wage in Texas of $7.25

Task	Time	Spent
Creating mold	0.5 hrs.	$3.63
Pouring plaster	0.5 hrs.	$3.63
Post processing	2 hrs.	$14.50
Total		$21.75

Machine time/machine hour cost

Machine hour cost can be calculated by dividing the cost of the machine by the total hours it should function, and multiplying that result by the time that the machine was in use.

There were no machines used for this project, it was all done by hand!

Project total: $27.62 (for 4 casts, 2 of which were completely post-processed)

Overall, I am happy with the outcome and look forward to making more molds in the future!