The Enclosure Is the Hard Part
The electronics take a weekend. The box that makes it a thing rather than a hazard you have grown fond of takes three.
Every project on this site has the same shape. The interesting bit works in an evening or two. Then there are three more weekends of box.
Nobody writes about the box. It photographs badly, it is not clever, and no part of it is a discovery. It is also the whole difference between a thing on your bench and a thing in your house, so here are the rules I have arrived at by getting them wrong.
Design the openings before the outside
Every enclosure I designed shape-first had to be redrawn, because a USB-C socket needs 3mm of clearance behind the panel for the plug's overmould and I had given it 1. Place the connectors, the button, the vent and the mounting holes first. Wrap the shape around them last. The outside is the easy part and it should come last, not first.
Heat-set inserts, always
Printed threads strip. They strip on the second open, which is always the one where you are annoyed already. Brass heat-set inserts are about two pence each, go in with a soldering iron and a spare tip in fifteen seconds, and turn a printed hole into something you can undo forty times. There is no version of this build where the box only opens once.
Strain relief is not optional and it is not a cable tie
The single most common way a home-built thing dies is that somebody pulls the cable and the solder joint goes with it. A moulded channel with a screw-down clamp costs you ten minutes in CAD and means the force lands on the plastic instead of your work.
Leave 2mm you did not think you needed
Wire has a bend radius. Connectors have overmoulds. Your neat mental model of the internal volume does not include the fact that you have to get your hands in there. Every enclosure I have printed to a tight tolerance has been reprinted at least once with more air in it, and I have never once regretted a box being 2mm deeper.
Print it in the ugly filament first
The first print is for measuring, not for keeping. Print it in whatever half-spool of unpleasant colour is nearest the machine, check the fit with real components, then print the good one. It costs an hour and it saves the material and the disappointment of a beautiful box with a hole in the wrong place.
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None of this is difficult. All of it is unglamorous, and that is precisely why it is where projects stall. The electronics were the excuse. The box is the work.
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