Our final concept is a 3D-printed Archimedes auger.

First sketch: a side-pivoting trough that pours over its long edge.

Pivot axis runs along the trough length L; the trough rolls sideways and pours over the full long edge.

Revised: a cam ramp keeps the rim engaged through the full rotation.

Rim stays in contact with the cam ramp throughout rotation; pours over the full long edge.

Cam-driven scoop — side, iso, and top views.

We screened seven candidate powders by hand-feel.

Rice flour · brown rice flour · sodium alginate · calcium lactate · carboxymethyl cellulose · xanthan gum.

Hand-scooping established the dose target — and the failure modes.

Pouring xanthan gum — youtube.com/watch?v=VAltAawtkA4

Powder clung to scoop walls; one sample stayed put after dumping.

Pouring rice flour — youtube.com/watch?v=IMuK3LTAWLM

Surface forces (electrostatic, van der Waals) dominate at this scale — Devora's call from issue #3.

A bistable snap-through trough was one alternative we explored.

The bistable mechanism has two energy wells at ±1.9 mm.

PR #5 — parametric OpenSCAD + FEA cross-check, peak snap 2.36 N, 23 passing / 1 skipped.

Commercial dispensers span lab balances to industrial feeders.

Edison Scientific surveyed the landscape — no off-the-shelf unit hit our μg–mg, low-cost, open-source target.

We considered eight concepts before converging on the auger.

Sterling Baird · Devora Najjar · Ron · with Nasa's help on the Ultimaker print.