Guides / Materials

Choosing Between Aluminium, Brass and Steel for a Case

September 21, 2026

Most of this decision is made for you. Aluminium is the material for a keyboard case, and almost every board you can name is aluminium with something heavier bolted inside it. The real question is which aluminium, and where the second material earns its place.

The three aluminium alloys that matter

6061-T6 is the default. It is everywhere, it machines cleanly, it is stiff enough for a thin wall, and it anodises acceptably in most colours. Its silicon content puts a slight grey cast into the oxide layer, so dyes come out a touch cooler and duller than on 6063.

6063-T5 is softer and lower in silicon. That makes it the better anodising alloy by a clear margin, with brighter and more even colour and a thicker, more uniform oxide film. It is also more forgiving to cut, with chips that break rather than string. The cost is stiffness: 6063 yields at roughly 214 MPa against 276 MPa for 6061-T6, so thin walls and long unsupported spans need more material.

7075-T6 is the strong one, and the wrong one for most cases. It is significantly stiffer, which matters if you are designing an unusually thin shell. Its zinc and copper content makes anodising dark, variable and hard to match between lots, and it costs more in both stock and tooling.

The short version: 6063 when colour is the point, 6061 when you want the safe default, 7075 only when the structure genuinely demands it. There is a fuller comparison in 6061 against 6063 for a keyboard case.

Brass

Brass C360 is free machining and cuts beautifully. It is also about three times the density of aluminium, which is exactly why people want it.

Almost nobody should make a whole case from it. A full size brass case can exceed four kilograms, which moves you into a different freight bracket, a different packaging problem and a price that will lose half your buyers. What brass is good at is the weight: a block machined to sit inside or under an aluminium case, giving the board the mass and the dead sound that people are actually chasing.

Brass patinas. Left raw it darkens over months into something many buyers love and some buyers return. Clear coating stops it and changes the look. Neither is wrong, but you need to decide which one you are selling and write it on the product page before anyone pays.

Copper

Copper C110 is heavier again, and visually extraordinary when it is fresh. It is also soft, gummy to machine and it starts darkening within weeks rather than months.

Copper is a weight material and an accent material, not a case material. If you use it, assume a clear coat, assume careful individual packing, and assume that a proportion of your buyers will be surprised by the patina no matter how clearly you explained it.

Stainless steel

304 and 316 stainless are used for weights and occasionally plates. They hold a brushed or bead blasted finish with no coating at all, which is a real advantage when you want a metal that just looks like metal.

The cost is machining. Stainless work hardens, so a dull tool or a hesitant pass makes the material harder in front of the cutter. Cycle times are long, tool consumption is high, and shops price it accordingly. Expect a stainless weight to cost several times a brass one of the same shape.

Titanium

Grade 5 titanium turns up in premium plates and the occasional halo case. The stock is expensive, the cutting is slow, and the process demands attention to coolant and feed that not every shop will give it.

Titanium colours by anodising too, but by an entirely different mechanism. There is no dye. Voltage controls the oxide thickness and the thickness produces an interference colour, which gives that characteristic range of blues, purples and golds and nothing outside it. Do not specify a titanium part in a Pantone colour.

A rough decision table

You want	Use
The safe default	6061 case, brass weight
The brightest, most even colour	6063 case, brass weight
Maximum stiffness in a thin shell	7075, and accept the colour limits
Weight and a dead sound	Brass weight inside aluminium
Metal that needs no coating	Stainless weight, brushed or blasted
A halo product with a halo price	Titanium plate, aluminium case

The part people get wrong

Designers reach for an exotic material to change the sound, and sound is mostly not a material question. The plate, the mounting system, the foam and the case thickness do far more to the acoustics than swapping one metal for another. If sound is the goal, start with the plate and the mount, then come back to the case metal.

The material decision that actually pays is the boring one: pick the aluminium that suits your colour target, put the mass in a separate weight, and spend the saved money on a prototype.

This is one part of our guide to keyboard case materials, which adds weight by layout, lead in brass and stainless steel.

Frequently asked questions

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