When it comes to replicating the characteristics of mainstream materials in the 3D Printing realm, there are only a few that can't yet be faithfully reproduced.

While colored and opaque glass are already being printed today, clear glass remains elusive because the current printing technologies introduce impurities that prevent the glass from reaching common expectations for what would commonly pass as "crystal-clear."

Fabrics, leathers, and wood are other materials that have yet to be replicated, because both natural and synthetic types have distinctive, hard-to-imitate features (like suppleness, tensile strength, and an inherent, two-dimensional flatness) that wouldn't be improved by printing.

There are also a variety of plastics that still don't translate in the 3D world, including the ever-popular plastic bag (due to its thinness).

3D Systems composed 0.36% of the T. Rowe Price Small-Cap Stock Fund's portfolio and 0.86% of the T. Rowe Price Small-Cap Value Fund's portfolio as of December 31, 2011. The following securities were not held by either one of the funds as of December 31, 2011: Bespoke Innovations, Jaguar, Bell Helicopters, Faro Technologies. The manager's views and portfolio holdings are historical and subject to change. This material should not be deemed a recommendation to buy or sell any of the securities mentioned.