I started off by making the 26.4% w/v alginate mixture to make a mold of my finger. Once it was well mixed I placed my finger in the alginate and waited for it to harden, forming the mold.

I then combined water and plaster of paris at a 1:2 water to plaster ratio, mixed it well and poured it into the mold. I allowed the plaster to set overnight and checked on it the next morning. I found that the plaster mixture I had made was too watery, and the finger had not properly formed. The plaster had settled at the bottom of the mold with a large volume of water above it. I was not able to take the finger out without ruining the mold, so I decided to make another one.

Later that day I came back and made another mold, but this time when I mixed the plaster of paris mixture I made sure to make it thicker. This time the plaster set perfectly, and the finger came out great.

However, when I cast the second finger using the same mold it came out with significantly more defects; this is most likely due to the mold breaking when I took the first finger. To make sure that I would get a usable second finger I made two more in parallel. They both came out great, so I proceeded to post-processing.

I removed and sanded any excess plaster before painting them a fun witchy green. After the paint had dried, I applied a clear coat to seal them.

This was a fun yet messy process. My main takeaway is if you want to reuse your molds make sure that the object is positioned in a way that makes it easy to remove without breaking the mold after casting.

Cleaned up workspace (Left the box so other people could use it to paint):

 

Cost Type	Cost	Price	Source	Quantity	Total
Materials	Alginate	$11.19	Joann	132g	$1.85
	Plater of Paris	$5.59	Joann	100g	$0.27
	Green Spray Paint	$5.98	Home Depot	1/50	$0.12
	Topcoat	$6.98	Home Depot	1/50	$0.14
Labor	Molder	$14/hr	Ziprecruiter	0.75 hr	$10.5
	Painter	$20/hr	Ziprecruiter	0.15hr	$3
	Prototyping Engineer (You!)	$36/hr	Ziprecruiter	3 hrs	$108
Overhead	Facility Cost	$65/month	FUSE Makerspace	3 hrs	$1.22
Total for a Prototyped Piece	$111.6
Total for a Piece	$17.1

The reason for the high prototyping cost is due to the high labor cost from the prototyping engineering (me!). However, this is much lower when using skilled labor that knows how to avoid issues with molding. Skilled labor should not take as much time as I did and would be working on multiple pieces at once so the time waiting in between steps would not be counted towards the cost of this one, which at under $20 is very reasonable for custome made pieces.