Filament in Plain Language

Filament is plastic string on a spool. The type of plastic decides how easy it prints, how strong the part is, and where you can use it. Start with PLA. Add others when you have a reason.

The four you'll meet first

PLA — the beginner plastic. Prints around 200°C on a 60°C bed, no enclosure needed, barely smells, sticks well. Downsides: brittle (snaps rather than bends) and softens in a hot car (~60°C). Perfect for decorations, organizers, prototypes, toys. If you're unsure, use PLA.

PETG — tougher PLA, roughly. Prints around 230–240°C, handles heat better (won't melt in the car), bends instead of snapping. Slightly stringier and fussier about settings. Good for functional parts that live indoors or outdoors: brackets, hooks, enclosures.

TPU — flexible, rubber-like plastic. Prints slowly (~220–230°C) and wants a direct-drive extruder. Great for phone cases, gaskets, feet, anything that should squish. Start with harder TPU (95A) before trying the squishy stuff.

ABS / ASA — strong, heat-resistant engineering plastics (~240–260°C). They shrink as they cool, so they warp and crack without an enclosure, and they smell — ventilate. ASA is ABS's weather-resistant sibling, good for outdoor parts. Don't start here; graduate to it.

The practical bits

Dryness matters. Filament absorbs moisture from the air, and wet filament prints badly (popping, stringing, rough surfaces). PETG and TPU are thirstier than PLA. Store opened spools in sealed bags or a dry box with desiccant. If prints suddenly get ugly, damp filament is a prime suspect.

Diameter and weight. Standard is 1.75 mm filament on 1 kg spools. Your slicer assumes 1.75 mm — don't buy 2.85 mm by accident.

Brands. There are dozens; quality varies more by batch than by logo. When you find a spool that prints well, note the brand — and re-tune temperature when you switch, even within the same plastic type.

Safety. PLA and PETG are low-odor and fine in a ventilated room. ABS/ASA need ventilation or an enclosure with filtration — the fumes are unpleasant and not something to breathe all day. Never leave any printer running completely unattended; it's a 200°C+ heating element.