We are back! This week I molded and casted two of my fingers. I began by measuring out 1.5 ounces of alginate in a 300ml silicone cup, as well as 6.75 ounces of water in another cup. I poured the water into the alginate and mixed until it was no longer clumpy. Once the mixture got thicker, I put two of my fingers in and waited for it to set. Once set, I pulled my fingers out.
Next, I moved on to making a positive impression with rockite. I measured 70 grams of rockite and 20 grams of water in silicone cups. I poured the water into the rockite and mixed thoroughly. I poured the mixture into the alginate mold. I added two screws to the 3D printed jigs and set them over the silicone cup using tape to set in the rockite. I cleaned the scale and washed the silicone cups in the bucket of water. I put the materials away.
I then came back the following day to remove my molded fingers. I was nervous trying to get the mold out of the cup without breaking anything, but it came out easily. I removed my rockite fingers. However, because I filled past the mold the fingers were connected at the top.
I removed the fingers from the 3D printed jig. I lightly broke off the outer pieces, to get the screw end to the appropriate diameter of my finger. I then lightly sanded to shape the ends into a circular shape to fit with the rest of the finger. Although my results turned out pretty well, if I were to do this again I would make sure to not overfill the rockite, and be able to avoid these steps all together. My screws are also not centered in my fingers. In the image below on the right, you can see that the screw head edge is slightly visible on the side of the left finger. If I hadn’t overfilled my rockite, I could have also better aligned the screws and have easily seen where the screws were placed in relation to the mold. However, the detail is minor and I assumed it wouldn’t be noticeable once post processing was complete. I determined that my molded fingers would still work adequately as hooks.
I then moved on to post processing. I set up my fingers in cardboard and spray painted them purple. This method allowed me to not get any spray paint on the screws and the bottom of the fingers. This will be better when I put them in a wall, because no purple will accidentally scrape off on the wall. I rotated the fingers three times, applying spray paint from the front each time, to ensure the entire finger got a nice coat. I set the fingers on the drying rack to dry.
I cleaned up my workspace, putting the spray paint back and throwing the cardboard away. I cut some foam and, once my fingers were dry, set them up to put on the table to turn in. Molding and casting fingers complete!
Cost Breakdown
Materials
- Alginate – $18.99
- Silicone cups – $9.49
- Screws – $0.2
- Rockite – $25.10
- Weight Scale – $7.99
- Popsicle sticks – $0.06
- Purple spray paint – $6.78
- 3D printed jig – provided by OEDK
Labor
$10 per hour for 2 hours = $20
Total Cost: $88.61
It would be significantly cheaper to create two additional fingers, because I would already have the alginate, rockite, cups and scale.
