To make the mold of my finger, I first mixed alginate powder with water. I didn’t measure the powder to water ratio, but poured the powder into about 5-6 oz of water until the mixture was similar to thick cake batter.

I molded my index finger and made sure not to curl the finger too much so I could get the concrete finger out easier and reuse the mold multiple times. When I was waiting for the alginate to set, indents of my knuckles also made it to the mold. These indents ended up helping me determine when the concrete finger was set: when the concrete spilled into these indents were set, I could take the concrete finger out in 1-2 minutes.

I used the Rockite concrete to make the finger. Again, I didn’t measure the ratio of concrete powder to water I used. With a tip from Elisa, however, I knew not to overdo it with the water: I poured about 2 oz of concrete powder, and added water a few mL at a time to mix it to an oobleck texture – seemingly solid, but flows when the mixing container was tipped. I poured the concrete into the mold and rolled it around to get rid of potential air pockets. I jerry-rigged a duct tape/ruler screw holder so I wouldn’t have to hold a wood screw in the concrete for 15 minutes.

The concrete set in about 15 minutes, but I let it sit for 20 minutes to ensure that it’ll be solid. Unmolding it was simple – I squeezed the alginate mold a bit to release the seal on the finger, and popped it out with ease. I was surprised at all the details the mold retained, especially all the small wrinkles. Unfortunately there were small air pockets that remained in the finger, but I filled it in with leftover concrete.

After sanding the fingers, I first sprayed them with a coat of clear gloss coat. I then sprayed a layer of silver metallic spray paint, and finished with a final layer of clear gloss coat. Overall, I don’t really like the look of it just because it’s weird holding two copies of my index finger, but I was impressed with the detail and how detailed and lifelike the finger was.

Cost analysis:

• Luna Bean Create-A-Mold Craft Alginate Molding Powder for Life Casting (1 lb) – $16.50 (Amazon)
  • Assuming I used about 8 oz of alginate for 5 oz of water – $4.13
• Rockite Cement (10 lb) – $14.14 (Max Warehouse)
  • Assuming I used about 4 oz – $0.18
• Kid Made Modern Craft Sticks (100 ct) – $1.79 (Target)
  • Assuming I used 2 sticks – $0.04
• Phillips Flat-Head Satin Nickel Wood Screw Kit (21 pack) – $1.28 (Home Depot)
  • Assuming I used 2 screws – $0.12
• Krylon spray paint (1 can) – $3.98 (Amazon)
  • 2 cans (clear coat and silver) – $7.96
• Labor cost (assuming Texas minimum wage of $7.25/hr) at 1.5 hours – $10.88
• Total cost: $23.31