The stock creality extruders are pretty trash. They have a tendency to not grip the filament well enough, or alternatively, grind the shit out of it leading to slippage.

My first upgrade on those machines is always a dual gear extruder. There should be a drop-in replacement for <$20 on Amazon. They’re almost always coated in red paint, should make it easy to find :p

I have a pack of M2-M5 screws + nuts + washers thats come in handy. Also, heat press inserts (if you have a soldering iron) can really help clean up designs. Again, I just have a M2-M5 pack with various lengths, and I think it even came with the soldering iron tips for each insert size.

I’ve had trouble finding Metric fasteners in my local hardware store, so I just buy variety packs online. Also, most 3D prints Ive run into use Metric sizes, with the occasional 6-32 screw here and there.

Zip ties are nice if you mess around with your printer or work on electronics (cable management).