Great for functional parts that need to flex without cracking: hinges, clips, snap-fits, containers, bottle caps, and tool handles. PP is tough, chemical resistant, and won't absorb water, so it handles workshop use well. A good first material if you're new to injection molding.

Store sealed in a cool, dry place away from sunlight. PP doesn't absorb moisture so no drying is needed, but UV makes it brittle over time.

Pellets are non-hazardous and safe to handle. Molten plastic is the real hazard: it sticks to skin and burns deeply. Wear safety glasses and insulated gloves around a hot machine. If molten PP contacts skin, cool under running water and immediately get medical attention.

Work in a ventilated area. Overheated PP gives off irritating fumes, and smoke means your barrel is too hot.

PP is recycling code 5 and one of the easiest plastics to reprocess. Sprues, runners, and failed shots can be shredded and run again through the machine with little loss in quality, so almost nothing has to be thrown away.

PP is chemically inert, contains no reportable hazardous substances, and is not listed as a carcinogen by NTP or IARC. Waste that can't be reused goes to regular landfill or industrial incineration. Check local rules, most municipal programs accept #5 but not all.