Casting sands are naturally occurring or synthetic materials used to make molds and cores for metal castings. The most common type of sand used for casting is silica sand, due to its widespread availability and favorable properties for metal casting.

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Czech Casting is a long-running adult reality series from the Czech Republic. It is known for its "street-casting" format where a host recruits everyday people for photo shoots and videos. In the case of Sandra (Entry 2135)

While the series is known for its "street casting" format, Sandra's episode is often cited as the gold standard for the "girl next door" appeal that the producers aim to capture.

Another angle: "Casting" can refer to the process of forming objects by pouring molten material into molds. If Sandra 2135 is a type of mold or casting method, the user might be looking for a guide on how to effectively use or produce that. But without more context, it's hard to say.