This week was about molding and casting. Images 1–8 are from the group assignment (SDS review and test casts). The rest document my individual project: casting the Snake Talisman from Jackie Chan Adventures — a palm-sized coin that grants invisibility, which feels fitting because I was born in the Year of the Snake.

Assignments

  • Group: review Safety Data Sheets for molding/casting materials; make and compare test casts; compare mold-making processes.
  • Individual: design a mold for a chosen process, produce a smooth master, and cast parts from it.

Group assignment (1–8)

As a group we read through the SDS for silicones, plasters, and resins, focusing on ventilation, gloves, cure inhibition, and cleanup. Then we mixed several materials and poured small tiles to compare detail resolution, pot life, curing time, and bubbles.

Group samples table
1. Table of group test samples: different silicones and casting materials side by side.
Opening silicone A/B
2. Opening A/B silicone components and checking the mix ratio on the labels.
Weighing materials
3. Weighing each part carefully — SDS + scale before any mixing.
Mixing silicone
4. Mixing silicone slowly to avoid trapping too many air bubbles.
Pouring into test molds
5. Pouring test tiles in a thin stream to reduce bubbles.
Degassing step
6. Degassing / vibrating the mold to help bubbles rise before curing.
Curing samples
7. Curing tiles lined up so we can compare detail and shrinkage after demolding.
Reference positives
8. Reference positives we used to evaluate how well each material picks up fine details.
Group notes. We compared one-part RTV and two-part tin-cure silicone and chose a blue 1A:1B tin-cure for flexibility and forgiving mix ratios. For casting, a white plaster-like material made it easy to read small details and iterate quickly.

Individual — Snake Talisman (9–23)

For my own project I wanted to cast the Snake Talisman — a circular coin with a raised rim and a stylized snake glyph in the center. The plan was: design the relief in CAD, machine a smooth positive in wax, pour a silicone mold around it, then cast several copies and see how well the lines and rim read in hand.

Design → CAM → Wax master

I started from reference images of the original talisman, simplified the glyph, and added a small draft angle on the walls to avoid undercuts. CAM used a roughing pass with a flat end mill and a finishing pass with a ball-end mill to minimize visible scallops on the wax.

Reference board and sketches
9. Reference board with screenshots and sketches of the Snake Talisman.
Talisman concept art
10. Cleaned-up concept art showing the final glyph and rim proportion.
Two-part cavity layout
11. Two-part cavity layout in CAD, with the coin relief and registration keys.

Silicone mold

Once the wax positive was ready, I built a simple box around it and mixed a tin-cure silicone. A thin brush coat went on first to wet all the details; then I poured a thin stream from high above to help break bubbles. After curing, I cut the mold open, added vents where necessary, and closed it with the registration keys.

Mixing silicone A/B
12. Mixing the 1A:1B silicone carefully by weight before pouring.
Pouring silicone over the master
13. Pouring silicone over the wax master in a single, steady stream.
Demolding the silicone
15. Peeling the silicone off the wax master and checking that the snake lines are clean.
Closed two-part mold
16. Closed two-part mold with registration keys keeping the halves aligned.
Alignment check and vents
17. Alignment check and small vent channels carved into the highest pockets.

Casting tests

I did several casting tests to tune the pour, vents, and cleanup. The deepest parts of the snake glyph tended to trap bubbles, so I added thin vents and adjusted how I filled the mold. Once the mix and timing felt right, the coin came out with a crisp rim and readable symbol.

First cast from the silicone mold
18. First cast from the silicone mold — good overall shape but a few missing details.
Trimming sprue and flashing
19. Trimming the sprue and sanding off flashing around the rim.
Failed cast with bubbles
20. A failed cast where bubbles collected in the deepest grooves of the snake.
Close-up of finished talisman
22. Close-up of the finished talisman — the relief reads clearly in light and shadow.
Final coin in hand
23. Final coin in hand at the intended scale: a small, invisible-power token for the Year of the Snake.

Process notes

  • Vents & pour: the eyes and deepest grooves trapped air; adding 1–2 fine vents and pouring from the opposite side improved the yield.
  • Keys: three small hemispherical keys kept the mold halves aligned and reduced flashing.
  • Finish: sanding the rim after demolding makes the coin feel much more “real”; a thin acrylic wash and clear coat can push it toward the jade/stone look from the show.

What I’d improve

Next time I would raise the deepest snake lines by about 0.2–0.3 mm to reduce bubble traps and move the main sprue to the back edge so cleanup is faster and less visible from the front.