Desk companion, c. 2010s–2020s
A palm-sized shell around a tiny camera, a radio and one AA battery. Three switches do the clicking and a notched wheel does the scrolling. The screws hide under the slippery feet, so the first step is to peel those back.
The part your hand rests on. The two buttons are part of the same moulding: long tongues that flex at the back and press the switches below when you click.
Made of ABS or polycarbonate-ABS plastic, injection moulded, with a soft-touch coating and rubbery side grips.
The click you hear and feel does not come from the plastic: it is a tiny metal spring snapping over inside the switch under each button.
Est. cost to the maker $0.5–1.5
A rubber-tyred wheel on a plastic axle. One end of the axle sits in a rotary encoder that counts the notches as it turns; push the wheel down and it presses a third switch for the middle click.
Made of Moulded plastic hub, a rubber or silicone tyre with a ribbed tread, a steel pin at one end.
The steps you feel while scrolling are a small spring riding over bumps inside the encoder; wheels with around 18 to 24 steps per turn are common.
Est. cost to the maker $0.1–0.4
One ordinary AA cell powers the whole mouse. A small boost converter on the board raises its 1.5 volts to the steadier voltage the chips need.
Made of Steel can, zinc powder anode, manganese dioxide cathode, potassium hydroxide electrolyte, a printed plastic sleeve.
A wireless mouse can run for months on one cell because it spends most of its life asleep: sensor and radio wake up the moment it moves.
Est. cost to the maker $0.1–0.4
The other half of the radio link. It plugs into the computer and tells it the mouse is an ordinary USB mouse, so no driver is needed. It lives in a little garage in the mouse when you travel.
Made of Steel USB-A shell, a tiny circuit board with a 2.4 GHz radio chip and a printed antenna, a plastic grip.
Mouse and receiver talk on the same crowded 2.4 GHz band as Wi-Fi and Bluetooth; many designs hop between channels to dodge interference.
Est. cost to the maker $0.5–1.5
Everything that thinks: the optical sensor, a radio microcontroller, the three click switches, the wheel encoder, a power switch and the converter that boosts the battery voltage.
Made of Glass-fibre circuit board, the sensor chip, a 2.4 GHz radio chip with a printed antenna, snap-action switches, a mechanical encoder, a red LED.
The optical sensor is a tiny camera: it takes thousands of low-resolution pictures of the desk every second and works out how far the texture has shifted between them.
Est. cost to the maker $1.5–4.5
A single piece of clear plastic under the sensor. One end bends the LED's light down and out at a low angle across the desk; the other is a small lens that focuses the lit patch of desk onto the sensor.
Made of Optical-grade clear polycarbonate or acrylic, moulded in one shot.
Light skimming the desk at a shallow angle makes even tiny bumps cast shadows the sensor can track. That is also why clear glass, with no texture to see, can baffle an ordinary optical mouse.
Est. cost to the maker $0.05–0.2
The tray everything sits in. It holds the battery between two spring contacts, has a pocket for the receiver, a window for the sensor to look through, and the posts the screws go into.
Made of ABS or polycarbonate-ABS plastic, injection moulded, with nickel-plated steel battery contacts.
The faint round marks on the inside are where steel ejector pins pushed the still-warm part out of the mould. They are always placed on faces nobody is meant to see.
Est. cost to the maker $0.4–1
The hatch under the battery and the receiver garage. Two hooks at the back hold it in, and a springy latch at the front snaps it shut.
Made of The same moulded plastic as the shell; the latch is a thin finger of the door itself, shaped so it can bend thousands of times.
Snap latches like this one are designed so the plastic only bends a few per cent each time; any more and it would turn white and crack after a few battery changes.
Est. cost to the maker $0.02–0.1
Thin slippery pads stuck to the underside so the mouse slides instead of scraping. Peeling them off is how you find the screws.
Made of PTFE (the non-stick pan coating) film with a pressure-sensitive adhesive backing.
PTFE has one of the lowest friction coefficients of any solid, which is why the same material lines non-stick pans and glide pads.
Est. cost to the maker $0.02–0.1
Prices are rough ranges of what the manufacturer pays for each part, pieced together from published teardown and bill-of-materials estimates. They vary a lot between models, years and order sizes, and they leave out assembly, software, research, shipping and profit. The drawing shows a generic device, not any particular model.