What AJK said. Make sure everything works and you're able to print successfully. It should come with a small sample of (garbage quality) PLA filament, enough for like half a test piece.
So you should definitely get some more filament --> 1.75mm PLA in 1kg rolls. Inland brand from Microcenter is good stuff if you're nearby, otherwise eSun, Hatchbox, Overture and Reprapper have been good to me.
Afterwards, upgrade the bed springs to yellow springs or silicone, and replace with metal extruder, kit with both is $10-15.
Other optional QoL upgrades:
$10-35 Automatic Bed Level, many options(BL touch, CR touch, 3D touch, etc)
$10 capricorn ptfe tube
$20 PEI bed
$5 filament runout sensor
$20-60 dehydrator or filament dryer to dry "wet" filament.. oven can be used, but not recommended
$$$ Raspberry pi for octoprint --> remote managemnt software
I think we should start a new thread for 3D printing. And for those interested, yes, you can print reliable plastic lowers. No, it's not as straightforward as milling an AR lower.
