3D-printable development model
A complete starting point for downloading, measuring, slicing, printing and recording the first physical fit test.
Engineering baseline v1. Ready for a bench or mannequin test print. Physical fit and human use have not been approved.
Prototype status
Cassette v1 passes automated mesh checks, but it has not yet been tested with two physical phones, approved slicer profiles or load and quick-release protocols. Use the first print only on a bench or mannequin and record every finding.
What you are printing
The model holds an uncased iPhone 13 Pro and provides a 44 mm camera keep-out, connector and side-button openings, side wings and strap slots. It is generated from the official phone envelope and fixed mechanical clearances rather than a client-uploaded CAD file.
Before generating a custom model
Use a flexible, non-stretch tape and record whole millimetres. Ask another person to help if that keeps the tape level. Do not add extra slack: the generator applies its own geometry rules.
Important: measure head circumference, not head diameter. The second value is the straight outside-to-outside temple width.
Measure horizontally around the widest circumference, keeping the tape level and comfortably in contact with the head.
Accepted range: 500–650 mm. Nominal sample: 570 mm.
Measure the straight distance across the head from the outside of one temple to the outside of the other.
Accepted range: 120–170 mm. Nominal sample: 145 mm.
Repeat the measurement before generating a model. Do not average obviously different readings caused by a tilted tape or a curved measurement across the forehead.
What v1 calculates now
Change both values to see exactly which dimensions the current generator changes. This preview explains v1; it does not prove anatomical fit.
templeSpan = templeWidth
wing = (templeWidth − 78.12) ÷ 2
slotHeight = 8 + (headCircumference − 500) ÷ 50
The public 3MF/STL remains the fixed 570/145 mm sample. Never resize that file: scaling would also change the phone cavity.
Engineering review rejected circumference-to-slot height as an unvalidated fit rule. Use this calculation only to understand v1; v2 needs a fixed strap BOM and physical fit data.
First test print
Prefer the 3MF file because it declares millimetres explicitly. STL is supplied as a fallback and must also be imported in millimetres at 100% scale.
These are starting values for a non-wearable fit prototype, not an approved production profile. Adjust for the printer and material, then record every change.
Open the 3MF, confirm units and compare the reported bounds with this page.
Rotate the part, choose a stable orientation and check rails, lip, openings and overhangs layer by layer.
Apply the recorded prototype settings and review the estimated material, time and first layer.
Stay with the printer for the first layers and stop if adhesion, warping or support placement fails.
Let the part cool, remove supports carefully and deburr without changing retention surfaces.
Controlled bench check
Use an uncased iPhone 13 Pro over a padded surface. Insert slowly without pressing camera glass, buttons or connector. Stop immediately instead of forcing a mismatch.
Note printer, material, nozzle, layer height, orientation, supports, scale, phone measurements, insertion and removal observations, defects and photos. Mark every check pass or fail.
A tolerance or geometry problem becomes a new immutable cassette version. A safety-critical miss recalls v1; the published file is never silently replaced.
Nominal test package
These files are the deterministic nominal fixture for a 570 mm head circumference and 145 mm temple width. They are suitable for the first controlled print, not a personalized fit.
Cassette v1 · nominal sample
Watertight mesh, 230 triangles, millimetre units, generated by whichear-cad-v1.
Common questions
No. Cassette v1 is dimensioned only for an uncased iPhone 13 Pro and does not support MagSafe accessories.
No model other than iPhone 13 Pro is supported. Similar-looking phones can differ at the body, button and camera keep-outs.
No. The first print is for bench or mannequin inspection. The face interface, straps, loads, quick release and human-factors protocol have not passed their gates.
It is a reproducible nominal fixture. The generator can create custom geometry only after receiving head circumference and temple width within the published ranges.