EpiPen AirTag Case Upgrade

I sell a 3D-printed hard case for EpiPens. I need it redesigned to include a built-in Apple AirTag compartment so the case can be tracked if it's misplaced. I will supply the existing source file to work from. This is an *addition* to a working design, not a from-scratch rebuild — the existing case must be kept intact.

**The task:**
Add a purpose-built AirTag compartment that holds the tracker firmly with zero rattle, without adding noticeable bulk or introducing weak/fragile points. You can integrate it into an existing wall or as a low-profile external pod — your call, but show me your reasoning.

**Requirements:**
- Apple AirTag dimensions: 31.9 mm diameter × 8.0 mm thick. Design around these exactly, with a snug, retained fit (friction ring, snap lip, or captured pocket).
- The AirTag must be **removable** for yearly battery changes — not permanently sealed in.
- No rattle, no significant added bulk, no thin walls prone to cracking. The structural integrity of the original case must be maintained.
- Must be FDM-printable, ideally without supports. Design for PETG at 0.2 mm layer height, with sensible wall thickness and ~0.2 mm clearance on the AirTag pocket.

**Deliverables:**
- Editable source CAD in **STEP** format (mandatory), plus your native file (F3D, Shapr3D, SolidWorks, etc.).
- Print-ready **STL**.
- Full commercial rights and ownership transferred to me on payment.