You built the thing and it works. In your hands, on your bench, every time. Then a friend tries it, or it sits in the garage a week, or the temperature drops, and it stops.
That space between 'works for me' and 'works for anyone' is where a lot of backyard builds stall. It's almost always a handful of repeatable causes, the same ones over and over, and once you've seen them you start designing around them automatically.
1. You designed for one assembly.
The first one fit because you were there, nudging and sanding until it went together. The second one won't, because those adjustments lived in your hands, not in the model. If you can't build a second copy without the fiddling, the design isn't finished yet. Bake the clearance into the CAD and prove it by making one you didn't touch up.
2. Your fasteners are doing more than you think.
