I have a 3D printer now, and with it the full beginner's catalogue of ways a print can go wrong. The machine is fine. I am the variable.
The first print was the obligatory little calibration cube, and it came out beautifully, which lulled me into thinking I'd cracked it. The second was something slightly larger and it lifted a corner off the bed about a third of the way up, curling like stale bread, so the nozzle spent the back half of the job dragging the model around a heated plate. Warping. The classic. The model peels off the bed as it cools and unevenly contracts, and everything above the lift goes to ruin.
Every failure since has come down to one of three things, and never the firmware or the slicer settings I kept fiddling with. Bed adhesion: clean the plate, it picks up skin oils just from handling. Levelling: the gap between nozzle and bed on the first layer decides whether anything else matters, and "close enough" isn't. And impatience: snatching at a part before it's cooled, or yanking the next filament through without letting the hot end settle.
What I underestimated was how physical the hobby is. I came in expecting a software problem and got a thermodynamics-and-housekeeping problem instead. The slicer is the easy part. Keeping a heated surface clean, level, and at the right temperature whilst plastic shrinks unevenly on top of it is the actual craft. Early days, but the failed prints are teaching me more than the good ones.