A60 shape, E27 screw base
It looks like the old glass bulb, but inside it is a small power supply and fourteen tiny lamps on a metal plate. Nothing in it is meant to come apart: the dome is glued on, the board is screwed or pressed down, and the base is crimped onto the housing. It opens with a twist, a pry and a pair of side cutters.
The milky globe that gives the bulb its familiar shape. It hides the bright little LEDs and spreads their light into a soft, even glow.
Made of Polycarbonate, frosted by light-scattering particles mixed into the plastic; held on with a bead of silicone glue.
Behind it are fourteen points of light, each far too bright to look at directly. The diffuser trades away a little of their light, absorbed or bounced back inside, for a glow that does not glare.
Est. cost to the maker $0.03–0.1
Fourteen small LEDs on a round metal-backed board. Each yellow square is a light source a few millimetres across; they are wired in series, so the same current runs through them all.
Made of Aluminium-core circuit board (a thin insulating layer and copper over an aluminium plate) with white solder mask; LED packages of blue-emitting gallium nitride under yellow phosphor.
The LEDs actually make blue light. The yellow phosphor over each one turns part of it into yellow, and blue and yellow together look white to us. More phosphor gives a warmer white.
Est. cost to the maker $0.15–0.5
A pressed aluminium disc that the LED board is screwed to. It takes the heat from under the LEDs and passes it on to the housing.
Made of Stamped aluminium sheet with a smear of grey thermal paste.
LEDs are efficient, but much of the electricity they take still turns into heat inside the chip, and a hot LED dims and ages faster. Getting that heat away is what most of the bulb's metal is for.
Est. cost to the maker $0.03–0.1
The part that goes into the lamp holder. The threaded shell is one contact, the blob of solder on the tip is the other, and a ring of black glass keeps them apart.
Made of Nickel-plated brass or aluminium shell, black vitreous glass insulator, a tin solder tip; crimped onto the housing.
E27 means Edison screw, 27 millimetres across the thread. The design goes back to Thomas Edison's lamps of the early 1880s and still fits lamp holders made today.
Est. cost to the maker $0.03–0.1
The flared neck of the bulb. Its fins give the heat from the LED plate a large surface to escape from, and its collar holds the dome.
Made of Die-cast aluminium with a white plastic collar; in many cheaper bulbs the outer skin is plastic with only a thin aluminium cup inside.
A 9-watt LED bulb gives about as much light as an old 60-watt filament bulb, so its housing has far less heat to get rid of; that is why it can be plastic and still be safe to unscrew.
Est. cost to the maker $0.1–0.4
A plastic liner inside the metal housing. The driver slides into it, so nothing carrying mains voltage can touch the metal you hold when screwing the bulb in.
Made of Flame-retardant polybutylene terephthalate (PBT) or polycarbonate, sometimes glass-filled.
Every part of the driver carries mains voltage, a couple of hundred volts in much of the world. This thin wall of plastic is a large part of what makes the bulb safe to touch.
Est. cost to the maker $0.02–0.06
A small power supply. It turns the mains' alternating current into a steady, limited direct current, which is what LEDs need: too little and they are dim, a little too much and they burn out.
Made of Glass-fibre board; a bridge rectifier, an electrolytic capacitor, a switching chip, a ferrite inductor wound with copper, a fusible resistor and a few small parts.
The four-diode bridge flips the negative half of each mains cycle, the capacitor smooths the bumps and the chip switches current through the inductor to hold it steady. That capacitor, slowly dried out by heat, is often the part that ends a bulb's life.
Est. cost to the maker $0.15–0.5
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.