The starting point was a very basic metal enclosure. Inside was a thyristor rectifier controller — a key control unit used in power engineering systems.

This controller is rarely seen by people. Most of the time it sits inside metal cabinets together with other power equipment. You usually only notice it during scheduled maintenance or in emergency situations.

But it’s still a commercial product. It gets sold, compared, and evaluated like any other piece of equipment. A plain metal box wasn’t good enough visually. For several reasons, the client also wanted to move from a metal enclosure to a fully plastic one.

The controller had to look appropriate next to equipment from other manufacturers. No “homemade” feel. The look needed to be technical and minimal, without unnecessary details.

At first glance, it’s just a rectangular box. But even with that limitation, there are many ways to approach the design.

We explored several concepts and narrowed them down to a few options that worked best. Those were taken further and refined.

The client provided PCB drawings, so we could start building a proper model.

Internally, the controller was split into two zones. One contained control electronics. The other housed power components that generated significant heat during operation and required ventilation.

There were also safety constraints. The enclosure had to protect against electric shock and prevent particles larger than 1×1 mm from getting inside.

Injection molding was chosen as the target manufacturing technology.

Initially, the client planned to mount the PCBs on aluminum rails inside the enclosure. That approach was later dropped. Aluminum didn’t solve the thermal issues, and the final decision was to make the entire enclosure plastic.

One of the internal zones heated up noticeably, so proper ventilation became critical. That required changes to the internal structure and the enclosure geometry.
We spent time designing the ventilation openings so they worked thermally without breaking the overall look.

Color was another open question. We reviewed several options and checked how different colors would look on a real enclosure, not just in renders.

At some point, we realized we had missed openings for the status LEDs on the top cover. That had to be fixed as well.

The enclosure was sent for prototyping. The first prototype looked decent overall, but there was still work to do. Around the same time, the client slightly updated the main PCB, which also required adjustments.

There were many connector labels, so we prepared files for printing markings — not only for the front panel, but for the top cover as well.

The second prototype incorporated those changes.

The client was actively involved in the refinement process. Together we went through another round of changes and built a third prototype.

A common argument is that devices like this don’t need design — they sit in cabinets and nobody sees them. We hear this a lot.

But there’s a simple rule that directly affects sales: you can’t make your enclosure worse than the market leader if you want to stand next to them.

If there’s a strong foreign competitor in your segment, customers will compare you to that product whether you like it or not. And the comparison is rarely in your favor.

If you want to sell, look at the market leader first.