HDPE as the body of a 3-D Printer? I've been working on my own DIY 3-D printer recently, and I've been trying to experiment a little with different materials for the body. Someone suggested using HDPE (high-density polyethylene), since it works well on a CNC machine, which would make creating a number of prototypes easy. I know HDPE can also be used for filament, but I've never tried it before. Does anybody have any input on HDPE, or other potential materials for the body? I'm trying to avoid using wood, as I've had some poor experiences with it.
The main consideration when building the body/frame of a 3D printer is the stiffness.  The stiffer the material, the less the frame will deform under load, and the more accurate and repeatable your results will be.

UHMW has a Tensile Modulus of Elasticity around 120,000 psi (http://www.polytechindustrial.com/products/plastic-stock-shapes/uhmw-polyethylene)

Aluminium has a Modulus of Elasticity around 10,000,000 psi (Mott, Applied Strength of Materials, 5th Edition, depends on the specific alloy)

Aluminium is around 100 times stiffer than UHMW.