Good alternative to HDPE for FDM A while back, I had worked on building a Yostwerks Sea Cruiser. Now I'm thinking of trying to create a 3D printable (or 3D millable) version of the plans.

The original design uses cross-sections cut from a half-inch thick HDPE sheet. However, I am considering changing this out for one of the easier to print materials, but I cannot find any comparative information about stiffness HDPE versus other 3D printing materials.

Can I get a suggestion for a alternative to HDPE that is as stiff or stiffer as well as same density or lighter. The Kayak frame is expected to be compressing the cross-sections.

An example set of cross-sections is as below:


Please note that I have also considering changing the shape of the cross-sections to make stiffer yet lighter cross sections, but that will require some trade-off between portable sized cross-sections versus the stiffness of the cross-sections.
According to the chart on this page HDPE has a flexural modulus of between 0.75 and 1.575 Gpa; meanwhile PETG has a flexural modulus of 2.20 Gpa, meaning PETG is the stiffer material.

HDPE, by definition, has a density greater than 0.941g/cc.  PETG has a density of about 1.25g/cc.

So while PETG may be denser (depending on the HDPE used), it is more rigid, while not being too rigid.

PETG is quite printable using FDM.  If you were printing at a higher temperature and high % infill, I could see it holding up well enough.  I've printed heavy duty parts with it using a 0.8mm nozzle.