Add tensegrity build-kit & DIY-materials recommendations

[Copilot]

Issue requested suggestions for off-the-shelf kits and materials the team can buy to hand-assemble tensegrity structures as a complement to the multi-material 3D-printing workflow.

Changes

• New doc reviews/tensegrity-build-kits.md covering:

  • Commercial kits, rank-ordered for this project, with vendor links inlined and prices verified against vendor pages on 2026-05-15: Tensegrity Adventures Icosahedron ($27.00, free US shipping — 6-bar SUPERball topology, primary pick), Tensologic Premium ($68 USD; £58.20 UK / AU$69.90 / ¥12,642 JP — 18 struts → covers prisms / 6-bar / double-layer grids / Snelson-X), Oriental Trading STEM pack ($19.98 / 12, outreach), UGEARS shuttle stand ($68.99, optional). Each row says why it fits the project, not just specs.
  • Explicit "avoid" list (Clementoni Floating Dragon, Walmart/Wacky novelty kits, most Etsy decor kits) — fixed-geometry novelties with no usable strut count.
  • DIY bill-of-materials (≈ $40) for arbitrary topologies: birch / bamboo / 6061-Al / CF struts; shock-cord / Dyneema / TPU-printed tendons; knot vs. zip-tie vs. printed-PLA-cap connectors (the printed-cap option reuses geometry from cad/joint-design/).
  • First-six topologies to build, mapped 1-to-1 to the simulation pipeline: 3-bar T-prism → 6-bar icosahedron → Snelson X-module → 4-bar prism → double-layer grid → Pajunen truncated-octa.
  • Budget impact: suggested bundle is ≈ $162 total (≈ $122 kits + ≈ $40 DIY), absorbs into the existing $1,000 supplies line in sections/budget.tex — no proposal edit required.
  • All approximate-value markers use ≈ or "approx." instead of ~ to avoid the markdown strikethrough-render gotcha.

• README: added a Hands-on / fabrication resources section linking to the new doc.

Suggested first purchase (verified 2026-05-15)

Item	Qty	Cost
Tensegrity Adventures Icosahedron Kit	2	$54.00
Tensologic Premium Kit (Amazon B091BFKXRR)	1	≈ $68
DIY parts inventory (dowels, shock cord, ties)	—	≈ $40
Total		≈ $162

[sgbaird-alt]

cc @achris0520

[sgbaird-alt]

@copilot fetch validated links, include in markdown, and verify prices.

Also noting when you use ~ a bunch of times, sometimes it renders as a strikethrough in md previews.

[Copilot]

@copilot fetch validated links, include in markdown, and verify prices.

Also noting when you use ~ a bunch of times, sometimes it renders as a strikethrough in md previews.

Done in 466a8af. Fetched each vendor page and updated to verified prices: Icosahedron Adventures $27.00 (free US shipping), Tensologic Premium ≈ $68 (Amazon ASIN B091BFKXRR; £58.20 UK / AU$69.90 / ¥12,642 JP), Oriental Trading STEM pack $19.98 (was $21.99) for 12, UGEARS Discovery $68.99 (was estimated $80–100). Removed the never-verified "Tensologic Advanced" SKU — only the real "Premium" SKU remains. Inlined hyperlinks throughout §1 / §2 instead of only in the references section. Replaced every ~ with ≈ or "approx." to avoid the strikethrough-render gotcha. Recomputed bundle: 2 × Icosahedron + 1 × Tensologic Premium ≈ $122 + $40 DIY ≈ $162 total.