Why We Replaced Steel With Timber — And Ended Up With a Better Product
Most sustainability conversations in product design start with a compromise. Something has to give up performance, cost, or design freedom in order to become more sustainable. Our X-Cart project didn’t play out that way. We set out to solve a fairly ordinary brief, a mobile powered cart, and ended up questioning one of the most unquestioned material defaults in engineering design: that a structural cart has to be made of welded, powder-coated steel.
It doesn’t. And treating that assumption as a genuine question, rather than a given, is what led us to timber.
The brief, and the problem hiding inside the default answer
The client needed a battery-powered mobile cart, a workstation on wheels, for retail and logistics environments. The default answer to that brief, almost without exception across the industry, is a fully fabricated, welded box section, powder-coated steel frame. It’s the expected material, the expected process, the expected finish.
But looking closely at this default revealed a stack of real problems layered underneath it. Custom sheet metal fabrication is expensive to develop and slow to modify. Every design variation typically needs proving and, often, its own paint run. Powder-coated finishes look good on day one but scratches and imperfections are exposed with daily use, and maintaining that finish in the field is rarely practical.
Steel is also heavy, which matters enormously for a cart that a person has to physically push, pull and manoeuvre for a full shift.
Underlying all of it, steel and fabrication costs have become increasingly volatile — both in raw material pricing and in the energy costs of the fabrication and finishing processes themselves.
None of these problems are hidden or unusual. They’re just accepted as the cost of doing things the expected way.
“The default material isn’t always the right material — it’s just the one nobody questioned last time.”
In HDF we trust
We specified High Density Fibreboard (HDF) — a tougher, denser relative of standard MDF — as the primary structural material for X-Cart. On paper, that’s an unusual choice for a piece of mobile industrial equipment. In practice, it resolved almost every problem the steel default had created, and opened up design possibilities steel had been quietly closing off.
HDF is significantly lighter than an equivalent steel structure, which translates directly into less physical exertion for whoever is pushing the cart around a warehouse or shop floor for hours at a time. It's CNC machined rather than welded and painted, which sidesteps the volatility of steel and fabrication energy costs entirely. And structurally, for the loads and use case involved, it performs entirely adequately — the material wasn’t a compromise on capability, just a different way of meeting the same requirement.
What the material change unlocked, beyond sustainability
The environmental and cost case for HDF was strong on its own, but the more interesting outcome was what the switch unlocked in the actual design process. Because CNC machined HDF parts don’t need to be tooled, proved, or run through a separate paint line the way a modified steel part would, we could develop X-Cart around a small initial kit of parts that supports genuine customisation. A new world of different configurations, colours, and accessories, with minimal additional production cost. A design variation that would have meant proving and a new paint batch in steel became, in HDF, simply a different CNC file.
The material also changed what was physically possible in the design itself. Sheet metal fabrication is constrained by bend radii and tooling limitations. HDF let us work with the actual depth of the material, which opened up construction and assembly details, integrated cable routing, and LED light tracking built directly into the structure. Details that would have been difficult or impossible to achieve within the constraints of folded sheet steel.
A constraint, reframed as a creative challenge
None of this came from starting with ‘let’s use a sustainable material.’ It came from taking a set of real, practical constraints; cost, weight, finish durability, volatile material pricing, seriously enough to question whether the default material was actually the right one, rather than just the expected one.
That’s the pattern we’d encourage more broadly: what looks like an impossible constraint, examined closely and treated as a creative brief rather than a limitation to work around, is often exactly where the most engaging designs come from.
X-Cart wasn’t designed to be a sustainability showcase. It became one because we let the material question stay open long enough to find a better answer.
As the pressure toward genuinely sustainable products continues to grow across every industry, we expect — and hope — to be involved in many more briefs like this one, where a difficult constraint is exactly what drives a surprising, compelling new direction.
MAKE approaches material selection as a genuine design question, not a default.
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