SendCutSend instructions for getting metal mount created

Since I've never used SendCutSend before, it'd be nice to have a step-by-step set of instructions for ordering the 2U faceplate in metal from them (mostly what options to choose), and notes about potential costs and shipping times.

(There is no rush to do this of course!)

Separately, maybe someone in the community would like to organize a group buy? Logistics mostly kill that sort of thing, but if multiple people in one small region might want metal parts, it would save money to have one person order multiples, then distribute them locally.

And with flat 10" parts, shipping costs aren't that bad.

首先檢查 repository 中現有的 2U 面板文件以及目前關於 SendCutSend 的任何指南。記錄訂購選項、可能的費用、運送時間，以及任何有明確支援依據的團購說明；當讀者能夠按照步驟訂購金屬零件時，這項工作就完成了。

由索引模型根據 Issue 內容生成。