Polymaker’s Brand New Fiberon PET-GF15 – Flexible Engineering
In this video I put the new Fiberon PET-GF15 from Polymaker through its paces—printing in red, white, blue and black—and showing off just how well it performs, including flexibility tests, lots of models, and real-world printing speed and results.
What it is:
Fiberon PET-GF15 is a glass-fiber-reinforced PET filament (15 % glass fiber) designed to “bridge the gap between everyday usability and industrial performance”. 
It delivers exceptional stiffness, dimensional stability, and thermal resistance while remaining accessible to makers and desktop printers. 
Key specs:
• Bending strength: ~104 MPa, HDT up to ~133 °C (0.45 MPa after annealing) 
• Young’s Modulus (dry): ~4144 MPa 
• Tensile strength: ~59.9 MPa (XY) 
• Available colours: black, white, light grey, dark grey, blue and red 
Why I’m testing it:
Because I received spools in four colours (red, white, blue, black) and wanted to see how this “engineering-grade” filament handles on a maker-level setup—how flexible or “tough” it is, how clean the surface finish, how easily it prints, and how it handles stress or bending.
Even though Polymaker markets it for jigs, fixtures, automotive and industrial parts, I’m testing it on a variety of models to show you how it might fit into a YouTuber/3D-printer-hobbyist workflow.
In this video you’ll see:
• Unboxing and the four colours (red, white, blue, black)
• Printing a selection of models to show off surface finish, flexibility and structural strength
• Comparison of how each colour prints (any visible differences?)
• Flex- and bend-tests to illustrate how the glass-fiber reinforcement plays out
• My printing settings (nozzle, bed temps, speeds) + any tips/tricks I found
• A short survey / verdict of whether this is a good choice for maker-level users (and if you need hardened nozzles, enclosure, annealing, etc)
Settings & tips (from Polymaker):
• Recommended nozzle/hotend temp: ~280–310 °C 
• Recommended bed temp: ~70-80 °C 
• Because of the glass fibers: use a wear-resistant (hardened) nozzle for durability. 
• Polymaker warns: “PET-GF filament adheres strongly to textured PEI plates—allow plate to cool before removal or use a release agent” 
• Annealing: Not required unless you need very high heat resistance( ~80 °C) - “If your application doesn’t require heat resistance above 80 °C, you can use it directly without annealing.” 
Survey Call-to-Action:
👉 I’d love your feedback: After watching please leave a comment or do the poll:
• Which colour print (red, white, blue, black) did you like best?
• Would you use PET-GF15 for functional parts tooling jigs?
• Do you think the extra cost over standard PETG is worth it for your use-case?
• Would you prefer me to print more extreme flexibility/bending tests or heat-chamber tests?
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– Thanks to @Polymaker for sending the filament — and thanks to you for watching.