Link

Materials

The “ashby chart” relates density and stiffness:

ashby

Ben of CBA shows how lattices and metamaterials can expand this space here and here

I’ve put this table together for practical use:

Material Young’s Modulus (GPA) Density (kg/m^3) Cost for 6mm x 24x24” Machinability
HDPE 1 960 23 Easy
PLA 1.8 1240 ($30 / kg) 3DP
ABS 2 1050 52 Not Dimensionally Stable, but OK to Machine
Acetal (Delrin) 2.8 1300 89 Breezy, also lasers, and non-cracking
Nylon 6 3 1100 130 Painful
Cast Acrylic 3.3 1100 46 Breezy, esp. w/ Lasers
FR1/CE (Canvas / Phenolic) 6 ~1850 81 TBD, probably WJ Pain and Ease on SB
FR4/G10 (Fiberglass) 22 ~1850 98 Painful on a WJ, Slightly Easier on a Shopbot
6061 ALU 69 2710 87 Breezy with WJ, Painful on Shopbot
Steel 200 7860 ~ 200 Yes