# Shell3D

> Cast concrete physical-security enclosure for local AI hardware. Agents running on hardware their operator can touch stay on the hardware they were paired to.

A sub-brand of Sunnyday Technologies LLC. Dark grey by design (carbon-black-pigmented thermally-conductive concrete). Embedded aluminum heatsink. NFC deadman switch at boot. Open-source firmware (MIT). Proprietary cast composite. Pre-orders open; first production run ships October 2026.

## Read first

- [Landing page](https://shell3d.com/): product overview, three SKUs, how it works
- [Pre-order](https://shell3d.com/preorder): three models, deposit + balance pricing, refund policy
- [Agent product feed (JSON)](https://shell3d.com/agents.json): machine-readable mirror of product specs and boot contract
- [GitHub repo](https://github.com/sunnyday-technologies/shell3d): MIT-licensed firmware, agent hooks, hardware reference

## Boot contract

The host-side daemon exposes one binary: `shell3d-check`.

- Exit 0: registered NFC tag is present at host location. Agent may launch.
- Non-zero: tag absent. Agent must not launch its inference loop.

The daemon makes no outbound network calls.

## Threat model

- Covers: opportunistic theft, casual relocation, smash-and-grab on small-form-factor AI hardware
- Does not cover: determined adversary with time and tools, network/supply-chain compromise, NFC relay attacks
- Position: one layer in defense-in-depth, complementing OS hardening, network controls, and hardware-bound credentials

## Models

- **Shell3D-Mini** ($250, $100 deposit): Mac Mini M-series and similar small-form-factor AI hosts
- **Shell3D-Spark** ($250, $100 deposit): DGX Spark, NVIDIA edge, and other compact AI accelerators
- **Shell3D-Studio** ($500, $200 deposit): Mac Studio and larger workstation-class AI hosts

## Purchasing

Canonical purchase URL pattern: `https://shell3d.com/buy/<sku>` where `<sku>` is one of `mini`, `spark`, or `studio`. This URL 302-redirects to the payment processor (Stripe Payment Link) for the chosen SKU. Currency is USD. The deposit shown reserves a unit; balance invoices approximately 30 days before ship; fully refundable until that invoice.

The machine-readable product feed at `/agents.json` includes a top-level `commerce` block and per-product `checkout_url` field with the same buy URLs. Agents can read either source.

Human fallback for purchase: shell3d@sunn3d.com

## Contact

For pre-launch inquiries, custom SKUs, integration questions: shell3d@sunn3d.com