Tonometer Enclosure: Packaging a Medical Device Around Its Electronics
A handheld eye-pressure measurement device housed around a fixed transducer, PCB stack and battery — a 3D-printable shell built to a supplied connection diagram.
A tonometer measures the pressure inside a patient’s eye. The client had the sensing hardware working and needed it to become a device someone could hold and use.
The problem
Medical prototypes carry constraints that consumer products do not:
- The transducer position is clinical, not stylistic. Where it sits relative to the user’s hand determines whether a reading is repeatable.
- Everything inside was already specified — component dimensions, a connection diagram showing how the parts wire together, and an existing outer shell that had to be improved rather than replaced wholesale.
- The deliverable was a 3D-printable shell, so wall sections, clearances and fastening all had to suit additive manufacturing at prototype quantities.
Mid-project the client revised the transducer geometry — the part on top turned out to be a different size than first supplied.
The approach
- Model from the supplied data, not from the render. Component envelopes and the connection diagram were treated as the source of truth, with the existing STL and SolidWorks files used as reference for intent.
- Cable routing designed in. The connection diagram was used to keep wire paths short and untangled, because a prototype that fights its own loom is slow to assemble and easy to damage.
- Absorb the revision cleanly. When the transducer changed, only the interface features needed to move — the rest of the shell held.
- User-facing geometry checked against market references the client supplied, so the device felt like an instrument rather than a printed box.
The result
A complete 3D-printable enclosure housing the transducer, electronics and battery, delivered through the transducer revision and ready for prototype assembly.
Where this applies
Medical and instrumentation prototypes where the sensing hardware exists and the device around it does not. Send the connection diagram and the component dimensions — those two documents remove most of the guesswork.
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