If the first layer looks like spaghetti, stop hitting reprint.

Most hobby printers fail on the same three things: the bed is not actually level, the nozzle is too far from the bed, or the filament is not hot enough to squish. One failed square tells you more than five full prints.

The 10-minute check I run before I even open the slicer:

1. Clean the bed with dish soap, not just IPA. Grease from fingers is enough to kill adhesion.

2. Home the printer, then slide a piece of paper under the nozzle at all four corners. Same drag, or it is not level.

3. Print a one-layer 50mm square. If it looks like dental floss, drop Z offset a hair. If it looks like a scraped pancake, raise it.

If that square still fails, it is not the STL. It is the machine. Fix the machine first, then print the model.