Once the electronics worked and GhostTune was talking through GhostBridge, I thought I was getting close to the end.

I wasn’t.

The enclosure ended up becoming a project of its own.

I wanted something that looked like a finished device, not a PCB sitting loose in a generic electronics box.

That meant designing around the actual board, the DB9 connector, the USB-C port, the component heights, and the way the PCB needed to be held in place.

I also wanted the case to snap together instead of using screws.

That sounded simple too.

It wasn’t.

My first enclosure ideas looked fine in CAD, but once I started printing them I found out pretty quickly that features that look strong on a screen can be weak in real plastic.

Some locating features were too thin and broke.

The snap geometry needed more material.

The PCB could move more than I wanted.

The connector openings were close, but not quite right.

Then I started getting into the kind of adjustments I never expected to care about:

0.1 mm here.

0.15 mm there.

Make this tab a little thicker.

Move that rail outward.

Reduce the USB-C opening slightly.

I probably spent more time thinking about tenths of a millimeter than I had spent thinking about entire control panels in the PLC world.

The process became pretty repetitive:

change the model → print it → wait several hours → assemble it → find the next problem

A full print could take around seven hours, so every bad revision had a built-in waiting period before I got to find out what I had done wrong.

That made small changes feel surprisingly important.

One version had small locating features near the DB9 that were too fragile and broke off.

Those eventually got removed completely.

The snap sections got thicker.

The PCB retention changed.

The centering rails changed.

The connector openings changed.

Even after the whole thing snapped together correctly, I still had a little bit of PCB movement inside the case and had to decide whether it was actually a problem or just me trying to make everything perfect.

Eventually I got to a version that snapped together, held the board securely enough, lined up with both connectors, and looked like something I would actually be comfortable handing to someone else.

That was another milestone for me.

The project had gone from:

jumper wires and an idea

to

custom PCB + firmware + iPhone app + custom enclosure

At that point, GhostBridge finally looked like a product instead of a prototype.

The next realization was probably the most unexpected part of the whole project:

I had built it for an ECU, but there was really nothing ECU-specific about the bridge itself.