DROPPER: From First Prototype to Final Design
The full development log of the dropper, from a 38mm rough prototype through five iterations to a final straight-finned, screw-in design — and its accuracy testing.
Iterations
**17 Apr 2026 — v1.** First rough prototype created. Diameter was 38mm.
**1 May 2026.** Printed and tested; the fins broke off and the body was not dense enough.
**7 May 2026 — v2.** Experimental teardrop shape, two halves printed sideways and connected with 3D-printed pins. Proved ineffective due to lack of fins. Added one 14mm steel bearing for density and reduced the diameter to 20mm.
**10 May 2026 — v3.** Added helical fins (also experimental). Used two 14mm steel bearings in the lower part and a two-part assembly held together with one-way connections. Size increased to 28mm diameter for a 30mm barrel.
**16 May 2026 — v4.** Helical fins moved to the back after a better understanding of the dynamics.
**20 May 2026 — v5 (final).** Switched to straight fins that screw in, allowing for easy fin changes.
New Testing Method
We built a stand out of PVC tubes weighed down with bricks, with a mount for the dropper that adjusts for each hole and centers onto the target.
The target used 50cm-increment circles out to 250cm diameter:
- 50cm — orange
- 150cm — red
- 250cm — white
The dropper was released by hand via actuation of the obstruction block and allowed to drop with minimal disturbance in the water by a diver.
Results
Out of 10 trials: 7 orange, 2 red, and 1 between red and orange. Average deviation was 25mm–75mm.
