3D Printing with Recycled HDPE Bottles | How I Made Filament from Plastic Waste

When most people think about 3D printing with recycled plastic, the first idea is milk jugs, water bottles, and other cheap household plastics. It looks easy: melt them down, extrude some filament, and start printing Iron Man suits. A quick Google search, however, usually brings discouraging comments from experts: “Don’t bother, HDPE is impossible to print, it warps, layer adhesion is terrible, and it’s unusable.” Yeah… I’m gonna have to go ahead and sort of disagree with you there.

HDPE ? Umm Yeah...

What is HDPE and why use it in 3D printing?

High-Density Polyethylene (HDPE) is one of the most common plastics in the world. It’s used in shampoo bottles, milk jugs, cleaning product containers, and pipes. HDPE is lightweight, strong, resistant to chemicals, and fully recyclable.

These same properties make it interesting for 3D printing: it’s cheap, durable, flexible, and widely available as waste material. The big challenge is that HDPE has a high shrinkage rate, poor bed adhesion, and tends to warp badly — which is why most online “experts” dismiss it immediately.

1- Extruding HDPE Filament

I first tried to extrude HDPE pellets with a Filastruder. The result? A chewing-gum-like blob came out of the nozzle. So instead of raw pellets, I moved on to recycling shampoo bottles.

Without a shredder, I cut Head & Shoulders bottles into small 5mm chunks with scissors. It took weeks to collect enough plastic, but eventually I had enough to extrude filament.

Using a Filastruder at 150 °C with a 3mm nozzle, extrusion went smoothly — just very slow due to irregular chunks. After hours, I managed about 5 meters of filament, enough for a small print: the classic owl. 

HDPE 3mm filament and test prints

2- 3D Printing with Recycled HDPE Filament

First attempts were rough: HDPE filament simply would not stick to the bed. After testing, I found that Pattex glue worked well. Print settings: 150 °C nozzle, 0 °C bed, no cooling fan, speed between 40–60 mm/s.

2.1 – Printing at 0% infill

Here’s what I observed during the first test:

• Bed adhesion: terrible, parts warped quickly.
• Layer adhesion: surprisingly decent in some areas.
• Overhangs/travel: HDPE struggles with both.
• Details: some fine parts (like the owl’s body) printed well. The raft also stuck properly — adding more material improved adhesion. 

Quality of the HDPE 3D Prints - 0% infill

Notice body/middle part of the big owl

   

2.2 – Printing at 100% infill

With solid infill, results improved dramatically. Warping was still present, but not catastrophic. Layer bonding was excellent — similar to ABS or PLA. The printed test piece was strong, flexible, and looked injection-molded.

This proves recycled HDPE can work for direct, simple prints without supports or overhangs. Most online “don’t bother with HDPE” advice is just wrong.

Better results with 100% infill

3- Common Problems When Printing with HDPE

• Warping: inevitable, especially without a heated chamber. Large prints will be difficult.
• Adhesion: needs glue (Pattex worked best in my case).
• Smell: shampoo bottle plastics give off unpleasant odors during extrusion/printing.
• Material purity: not all bottles are 100% HDPE — blends may behave unpredictably.

4- How Does HDPE Compare to Other Plastics?

Compared to ABS and PLA, HDPE is harder to print but more flexible and tougher once printed. Compared to Polypropylene (PP), HDPE behaves similarly with warping and adhesion problems, but is far more available as waste. The biggest advantage? HDPE is free and everywhere.

Conclusion

My tests showed both 0% and 100% infill prints were successful, proving recycled HDPE filament is usable. The material is free, strong, and durable — but you need to accept its limitations. Warping is the main challenge, but with glue, smaller prints, or blending HDPE with ABS (ABS-HDPE blend), results can improve.

Bottom line: Yes, you can 3D print with recycled HDPE. It’s not perfect, but if you’re into experimenting, it’s worth trying instead of throwing those bottles away.