We get many print jobs that come to us from popular template design sites for frosted plastic cards and we have to unfortunately inform customers they will not get what they see in the design, or that the template was not made properly for a few reasons.
The most common mistakes is size, and colors. Some printers print on credit cards, and thus their templates are not business card sized. Our cards are standard US 3.5 x 2in. Some designs may have white in them and since we print offset in CMYK white does not print. Thus designs with white in them actually would be clear, and since printed on transparent material ALL colors will be transparent to some degree. In the example above that design would be completely clear with the black letters and brown letters being mainly the only thing visible. Darker colors show up better than lighter ones. For a visual example drop your transparency on your art 40-50% to get an idea of what it might look like after printed.
As you can see in this example, even the black is slightly transparent. This example reads well with the lighter background in the photo.