1.   Steel vs. Aluminum
    a.   Easier to machine or robust longevity
    b.   Strength vs. Weight Savings
2.   Natural vs. Hardened Materials
    a.   Datum surfaces machineable or shimmable
    b.   Cost Savings vs. Tooling Life
3.   Exotic Materials
    a.   Copper, Ampco 18 Bronze, Concast 954 Aluminum Bronze, Elkonite
    b.   Cost of Materials vs. Overall Tooling Performance
         i.   2 Diameter, 36 long Ampco 18 Bronze = $350.00 (O1 TS: