Fingers slid under a flexible skin on the back of a phone, so the phone hangs.

Design review · unmarked phone · concept study

The hold should be the phone.

You don’t squeeze a phone. You hang it on your fingers. This note asks for a rear skin that lets them in, and for a prototype of that skin before anyone designs a case.

For the room: read the decision, watch the side film, then the four tests.

The decision

Build the skin. Do not build a socket.

Fund one module: liquid silicone, bonded on a center keel, with a tucked lip. Not a full device. Not a ring, a strap, or a PopSocket. Pass or fail it on the four tests below.

1. Accept a replaceable rear skin, or keep one unbroken back. That is the real choice.
2. If yes, prototype the module only.
3. Ship it only if the hold, the pocket, the coil, and service all pass.

Why this exists

The accessory is a confession that the phone has nothing to hang on.

A phone is a smooth slab. The hand keeps it by clamping. Relax, and it slips. People buy a hinge and glue it over the wireless coil. It works until it snaps off in a pocket.

A groove does not hold once the hand relaxes. A flexible phone puts the coil and the battery in the wrong place. The flex should be a skin. The phone stays rigid.

PopSocketA hinge on the coil. It breaks.
A grooveNothing keeps the phone when the grip lets go.
A bending phoneThe coil and the cell need a hard plane.
ThisA skin. The phone stays a phone.

The part

Stuck down the middle. Open on both edges.

Rear of an unmarked phone with a flexible skin lifted along one side, showing the finger pocket. — At rest the skin is flush. One side is lifted here so the pocket is visible.

Skin: Liquid silicone, about 1.1 mm, Shore A 45.
Keel: An 8 mm bond down the center. The only attachment.
Entry: Both side edges. A 0.5 mm lip tucks the skin.
Pocket: Flush at rest. About 14 mm of stretch over two or three fingers.
Hard cap: Top 30% never flexes. Camera, coil, and NFC live there.
Frame: Antennas stay in the metal rail. The skin is not conductive.

Targets, not tolerances. The photographs are a look, not a built part.

In the hand

Watch the side film first.

From the side you can see the pocket. The skin is over the fingers and the phone is hanging. The thumb is still free, so the phone can be used one-handed.

The phone is hanging. The hand is not clamped.

A hand with fingers slid under the flexible back skin of a phone. — From the back. The thumb stays on the rail, so the screen is still usable.

Pass / fail

Four tests. All of them, or it does not ship.

01HoldEither hand, relaxed, keeps the phone for 30 seconds.
02PocketIn and out of a front jeans pocket, 50 times. No snag. No flap.
03CoilWireless charging and the camera match a hard back.
04ServiceThe skin comes off and goes back on without opening the chassis.

Say these in the room

The risks, before anyone else lists them.

The keel
This is the part that fails. Peel, sweat, heat, and a drop. Test the bond. Do not assume it.
Dust
The pocket will get dirty. That is why the skin is a module, not the structure.
Durometer
Too soft and it sags. Too hard and fingers will not enter. The rubber is the design.
Thickness
About 1.2 mm where the skin sits. That is the budget. It does not grow in a pocket.

What this is not: a flexible battery, a bending chassis, or a skin laid over the coil. It is also not affiliated with Tesla, SpaceX, or X. The films are a study of the hold.