Sheet metal, aluminum extrusion or CNC: which metal electronics enclosure fits a first production run?

For a first, low-volume run of dozens to a few hundred units, a metal enclosure is usually bent sheet metal, an off-the-shelf extruded aluminum enclosure with your own end panels, or a shell machined from solid aluminum when the look is the product. Sheet metal, stock extruded enclosures and CNC machining need no tooling, and first parts take days to a few weeks. A custom aluminum extrusion starts to pay at about a thousand units a year and up, but the extruder's usual minimum order, often 1,000 to 2,000 pounds of profile or about 2,000 to 4,000 housings of 150 × 100 × 40 mm, means buying a few years of housings at once, unless you find a smaller extruder or pay a minimum charge. The extrusion die itself cost about $1,000 to $4,000 at North American extruders in 2019. Die casting and stamped sheet metal usually pay from about 5,000 to 10,000 parts a year. Other prices in this post come from shops, distributors and trade sources dated 2019 to November 2026, and tariffs are as of November 2026.

Two things matter as much as the process: radio and grounding. A closed metal box acts as a Faraday cage and blocks radio signals, so a Wi-Fi, Bluetooth or cellular antenna needs a plastic end cap, an RF window or an external antenna, and a design whose range was fine in a 3D-printed case often loses it in metal. Anodizing, an electrochemical treatment that grows a hard oxide layer on aluminum, and powder coat, a dry paint powder sprayed on and baked, are electrical insulators, so wherever the board's ground, a connector or a panel has to touch the case, the finish has to be left off or replaced with a conductive one.

What does each process make well?

Bent sheet metal. Flat sheet is laser- or punch-cut, bent on a press brake into a U-shaped base and a cover, fitted with threaded inserts pressed into the sheet (self-clinching nuts and studs), and powder coated or anodized. It suits box shapes: controllers, chargers, routers, test gear. Online sheet-metal shops price a bent part about 120 to 165 mm on a side and 1.5 to 3 mm thick at about $45 to $75 for one and $16 to $25 each for 100, including inserts and finish, so a two-part box costs roughly twice that. Bending leaves faint lines that powder coat hides and anodizing often doesn't, and dimensions that cross bends are looser: for sheet up to about 3 mm thick, one large shop holds ±0.13 mm between cut features, ±0.38 mm across two bends and ±0.76 mm across three or more.
An off-the-shelf extruded aluminum enclosure. A stock extrusion with slots that hold the board, closed with flat metal or plastic end panels, sold through electronics distributors in dozens of sizes. A box about 160 × 103 × 53 mm costs about $34 for one and $22 each for 100 from a major distributor. You pay to have your own end panels cut or machined with the openings for connectors, buttons and lights, and printed with your labels. A plastic end panel at the antenna end is the simplest way to get a Bluetooth or Wi-Fi signal out of a metal box.
A custom aluminum extrusion. Your own cross-section, pushed through a die, then cut to length, machined for ports, anodized and closed with end caps of metal or plastic. North American extruders priced dies at $1,000 to $2,000 for solid shapes and $1,200 to $4,000 for hollow ones in 2019 figures from the extruders' trade association, so expect current quotes to be higher, with dies ready in two to four weeks; Asian suppliers quote less. Molded plastic end caps need an injection mold of their own. Keep the cross-section small enough to fit inside an 8-inch circle, the size the most extrusion presses can run, round the corners, avoid big jumps in wall thickness, and keep channels no deeper than three times their width.
CNC machining from solid. A shell milled from a block of aluminum, usually 6061: the "unibody" look of many laptops and premium devices. No tooling, almost any shape a cutter can reach, and ±0.1 mm is a typical tolerance. The cost is machine time, which quantity doesn't remove: a pocketed shell can take from half an hour to several hours to machine, depending on how deep the pockets are and how many times the part has to be re-clamped. At one online shop, a small anodized aluminum part about 64 mm square costs about $357 for one and $73 each for 100. Inside corners can't be sharp, because the cutter is round; a common rule is a corner radius of at least a third of the pocket's depth.
Die casting (die-cast aluminum or zinc), for later. Molten metal injected into a steel die, the usual metal process at high volume. Dies cost from about $6,500 for a simple part made in Asia to $20,000 to $100,000 or more, take weeks to months with sampling, and usually pay from about 5,000 parts a year. Die-cast aluminum anodizes poorly and conducts heat only about half to two-thirds as well as the aluminum used for sheet, extrusion and machining, and the parts are usually painted or powder coated.

How do sheet metal, extrusion, CNC and die casting compare on tooling, lead time and minimum order?

The table compares the five options for a small electronics enclosure, about 150 × 100 × 40 mm (about 6 × 4 × 1.6 in): the one-time cost, the time to first parts, the minimum order and the yearly quantities where each usually fits. Prices are from online shops, distributors and trade sources dated 2019 to 2026.

Process	One-time cost	First parts	Minimum order (MOQ)	Usual quantity per year
Bent sheet metal	None; a stamping die, about $12,000 to $35,000, pays only at thousands a year	Days to two weeks	None; finishing lots may carry a minimum charge	10 to a few thousand
Off-the-shelf extruded enclosure	None; custom end panels are paid per part	Days	None	1 to a few thousand, if a stock size fits
Custom aluminum extrusion	Die about $1,000 to $4,000 in North America in 2019, less in Asia; molded plastic end caps need their own mold	Two to four weeks for the die, then parts	Often 1,000 to 2,000 lb of profile, about 2,000 to 4,000 housings	About 1,000 to tens of thousands
CNC machined from solid	Programming and setup, usually tens to hundreds of dollars a job	Days to two weeks	None; finishing lots may carry a minimum charge	1 to a few hundred, more when the look is the product
Die casting	Die about $6,500 for a simple part made in Asia, to $20,000 to $100,000 or more	Weeks to months, with sampling	Usually thousands	About 5,000 and up

How does the cost change with quantity?

Sheet metal has no tooling at these quantities. At online shops, the price per part falls two to six times between one part and 100, then flattens. At about 5,000 to 10,000 parts a year, a stamping die can beat laser cutting and bending, but the die takes 8 to 18 weeks to build and fixes the design.
Extrusion spreads a small die cost over many housings, and each housing is mostly metal, cutting, machining and finish. Extrusion's catch is the minimum run: below a few thousand housings, you either buy more profile than you need, pay a minimum charge, or find an extruder with a smaller press.
CNC machining spreads its setup over the first few dozen parts; after that, the price per part (the unit cost) barely falls, because every part still needs its minutes on the machine.
Die casting has the lowest price per part at volume and the highest tooling cost and longest wait, and it locks the design in.

Sheet metal, extrusion, CNC and die casting aren't steps every product has to climb. Many products stay in sheet metal or extrusion for life. Moving from one process to another means a new housing design, new fits with the boards and buttons, new first samples, and often a new radio check: a range test in the new case and, because the case changes what the product gives off, a question to your test lab about whether the FCC tests have to be repeated. See Which US tests does an electronic product need before you sell it.

What changes when electronics go into a metal case?

Radio. A closed metal box acts as a Faraday cage and blocks radio signals. The usual answers are a plastic end cap or RF window over the antenna, an external antenna on a connector, or a slot cut into the metal, which takes antenna (RF, radio-frequency) design work. One Wi-Fi chip maker recommends at least 15 mm of clearance around a module's board antenna inside a housing, and testing range in the finished product; Bluetooth uses the same 2.4 GHz band, so plan the same room. Decide where the antenna goes before the enclosure is frozen, and test range, and run the FCC tests, in the real metal case, not a printed one.
Grounding and EMI shielding. Anodizing and powder coat insulate. Mark in the drawings where the board, connector shells or panels must touch the case, and have those areas masked, often with a conductive chromate conversion coating (chem film, MIL-DTL-5541) instead. For shielding against electromagnetic interference (EMI), the seams and openings leak, not the walls: close screw spacing, overlapping flanges or conductive gaskets keep a seam tight. A conductive gasket can cost you water sealing: one maker rates the shielded version of a sealed box IP54 (dust-protected, splash-resistant) instead of IP65 (dust-tight, resists water jets). For sealing a housing against water, see How do you make an electronics enclosure waterproof (IP67) for production?
Heat. The aluminum used for sheet, extrusion and machining conducts heat about three times better than carbon steel and more than ten times better than stainless steel. To use the case as a heat sink, give the hot chip a raised pad on the inside wall and a thermal pad between them, with the finish masked there if needed. Bare aluminum radiates heat poorly; an anodized, painted or powder-coated surface radiates about eight times as much, which in still air lets the case shed roughly 1.5 to 2 times the heat at the same temperature, and white powder coat radiates about as well as black. A case that sinks heat also gets warm, and safety standards limit how hot a surface people touch can get.
Mains safety. If anything inside runs from mains (AC) voltage, an accessible metal case has to be connected to protective earth through a three-prong cord, or the mains circuit has to be double-insulated from it, and the safety lab tests that. With a listed external adapter and only low voltage inside, this doesn't apply.
Static. A metal case people touch needs a planned path for static discharge. Decide where, and through what, the case connects to the circuit's ground, rather than leaving panels unconnected ("floating"); otherwise a static spark from a finger can jump to the board and reset or damage it, even in a battery-powered device.
Corrosion. Zinc-plated or stainless screws in aluminum are normal indoors. Outdoors or in damp places, use isolating washers or sealant, and keep bare steel off bare aluminum.
Weight. At the same wall thickness, steel weighs about 2.9 times as much as aluminum. An extruded aluminum box about 160 × 103 × 53 mm with 1.5 mm walls weighs about 0.3 kg with its end panels.

Anodizing or powder coat, and why don't colors match between batches?

Anodizing. Type II, the decorative kind, is about 10 to 25 micrometers thick in clear and colors. Type III, hard anodizing, is about 25 to 50 micrometers, comes in black or natural, and costs considerably more; about half of it builds up on the surface, so allow for it in tight fits. Colors aren't matched from one order to the next: the same "black" varies between batches and between alloys, so a 6063 extrusion, a 5052 sheet-metal cover and a 6061 machined cap rarely match exactly. Finish parts that sit side by side in one batch, keep to similar alloys, and agree on a color range with limit samples, the approved light and dark ends of the range. Dyed colors fade in sunlight.
Powder coat. Adds about 0.05 to 0.13 mm per side, so leave room in fits and threads. It covers bend lines, comes in standard colors, and holds a color more evenly than anodizing.
Bead blasting before anodizing hides machining marks and gives the matte look of many laptops.

Do US metal tariffs apply to an imported metal enclosure?

As of November 2026, under Section 232, the US national-security tariff on metals, goods made entirely or almost entirely of steel or aluminum have paid a 50% tariff on their full customs value since April 6, 2026, and a metal housing imported on its own may be classified as one. A finished electronic device pays a Section 232 tariff only if its tariff code (its HTS number) is on the list of derivative products, and then usually 25% of its full value. Listed goods outside the metal chapters of the tariff schedule that are less than 15% metal by weight pay none. Classification is decided case by case, so confirm it with a licensed customs broker. If the enclosure is made where the product is assembled, it enters the US inside the finished device rather than as a separate metal article. For the other tariffs on the finished product, see US tariffs on electronics from China, Korea, Vietnam and Mexico.

Example: one housing, three ways

This is an illustration, not a customer project. The product and all the numbers are made up.

In this made-up case, a desk device with a Bluetooth module needs a housing about 150 × 100 × 40 mm: a made-up 200 units first, then a made-up 2,000 a year if it sells.

CNC from solid, with a plastic window over the antenna (made-up numbers): $140 a housing at 200 units, $28,000. It looks the best, but at a made-up $90 each, 2,000 a year would cost $180,000.
Bent aluminum sheet, two parts, powder coated, with a plastic window over the antenna (made-up numbers): $50 a housing at 200 units, $10,000, with no tooling. At 2,000 a year, a production shop might charge a made-up $25 each, $50,000 a year.
Custom extrusion with molded plastic end caps (made-up numbers): a $2,500 die, a $4,000 aluminum mold for the end caps, and a minimum run of about 3,000 housings at $13 each, including cutting, machining, anodizing and end caps: $45,500 before the first unit ships. At 2,000 a year after that, about $26,000 a year in this made-up case.

In this made-up example, sheet metal fits the first 200: it costs less than a quarter of the extrusion's first bill and needs no tooling. Moving to extrusion later costs the die and the end-cap mold plus a made-up $8,000 to redesign the housing, sample it and recheck the radio through the new end cap, $14,500 in all, and saves a made-up $12 a housing ($25 against $13). With these made-up numbers, the switch pays back after about 1,200 housings, about seven months at 2,000 a year, but the first extrusion order is still the made-up minimum of about 3,000 housings: $39,000 in cash for a year and a half of housings. Starting in extrusion skips the switch but, at that made-up minimum, commits the team to 3,000 housings before it knows the product sells.

The general rule: start where tooling and minimums are smallest while the design and demand are uncertain, and move to the process with the lower price per part once the quantity pays back the tooling and the switch.

What should you ask a metal shop before ordering?

The material, alloy and thickness, and which faces are cosmetic.
The tolerances on dimensions that cross bends or joints, and how they'll be measured.
The finish: the type, the color range, whether parts that sit side by side are finished in one batch, and limit samples for color and scratches.
Which areas are masked for grounding, and what finish they get instead.
The inserts and threads: whether they go in before or after finishing (on anodized parts, usually after), and whether threads are masked during finishing.
The minimum order or minimum charge, for the parts and for each finishing lot.
For extrusion: the die cost, who owns the die, the minimum run, and whether the die cost is credited back above some volume.
The lead time including inserts and finishing, not just cutting.
How the parts are packed to protect the finish.
Where the parts are made, for tariffs.

For the plastic side, see Aluminum or steel injection molds for a first production run; for low-volume processes, 100 to 1,000 units: bridge tooling, urethane casting or machining?.

Where we come in

If you're choosing between sheet metal, extrusion and machining for your first run, this is one of the situations Anamor takes on. We design each part for the process that will make it, from sheet metal, extrusion and CNC machining to molded plastic, at the quantities you're planning, and our quotes list setup costs separately from unit prices. If a metal enclosure doesn't pay at your quantity, we suggest another process, or tell you plainly if we're not the right fit.

Anamor takes US hardware teams with a working prototype into their first production run: we redesign the product for production, line up partner factories and suppliers in the US and overseas, price it at your quantities, and run the build through to shipping.

Send what you have: photos of the prototype, CAD if you have it, where the antennas, connectors and hot parts sit, and how many you plan to make, now and over the next few years. Need an NDA? We'll send our mutual NDA, or review yours, before you send files. Within two business days, a real person on our team will reply with a free first look at your production run and a few times to talk.

Frequently asked questions

Is sheet metal or CNC machining cheaper for a small electronics enclosure?

At low volume, usually sheet metal. A bent two-part box needs no tooling, and online shops price a bent part about 120 to 165 mm on a side at $16 to $25 each for 100. A machined aluminum shell costs more, because every part needs machine time; it fits a few hundred units or a product whose look justifies it.

When is a custom aluminum extrusion worth it for an enclosure?

From about a thousand units a year. The die cost about $1,000 to $4,000 at North American extruders in 2019, but the usual minimum order, 1,000 to 2,000 pounds of profile, is about 2,000 to 4,000 small housings, so you buy a few years of housings at once unless you find a smaller extruder or pay a minimum charge.

Will Bluetooth or Wi-Fi work inside a metal enclosure?

Not through a closed metal box, which blocks radio signals. Put the antenna behind a plastic end cap or window, use an external antenna, or cut a slot designed as an antenna. Leave clearance around the module's antenna, decide where it goes before the enclosure is frozen, and test range and run the FCC tests in the real metal case.