Apple currently manufactures most of its product casings in aluminium - and increasingly recycled aluminium, including in the Mac mini. But the company appears to be exploring its options for alternative metals.

Titanium is a much stronger metal than aluminium. Admittedly the density is higher, but a case made of titanium can be far thinner while offering the same strength, with the result that the product is lighter.

In a recently published patent application, Apple writes about technologies that can be used to make the titanium exterior of a portable electronics product more attractive by combining polishing and anodising, reports 9to5Mac.

The most interesting thing about the patent is that it shows how titanium can be used on the Mac, iPhone and iPad, as well as the Apple Watch that's currently offered in a titanium option.

If Apple does start making the MacBook in titanium, of course, it won't be the first time. Between 2001 and 2003, the company sold the PowerBook G4 in titanium, commonly known as the TiBook. And in 2007 there was a rumour that it was going to make a titanium iMac, although that never came to anything.

Given that Apple already manufactures the Pro models of iPhone in steel instead of aluminium, the company may be planning to replace the steel with lighter titanium.

For more clues about upcoming announcements, read our guide to the new Apple products coming in 2021.

This article originally appeared on Macworld Sweden. Translation by David Price.