The Sunlu PLA+ filament refills (available on Amazon and elsewhere) are a great option, but don't fit the Sunlu “MasterSpool” they're sold with, resulting in loose filament, tangles, and AMS/printing errors. This adapter fits a BambuLabs white spool and makes the Sunlu refills a perfect fit, so there are no tangles or errors.
Built using a hex/honeycomb pattern to reduce the filament used in printing (only 45g).
My settings:
Generic PLA settings
0.4mm nozzle
0.2mm layer height
0.42 layer width
2 wall loops
No supports
Speed doesn't matter; I recommend leaving door open on enclosed printers and turning on the part cooling fan to facilitate cleaner bridges.