现在的模型是由几层膜和一个金属化的背框组成的。

The current prototype is constructed from a number of films and a metallised back-frame.

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关键制模工艺包括：母模制备、金属型壳制造、模框制作、背衬强化层制作、脱模以及后处理等。

Arc spray tooling process mainly includes: master pattern preparation, surface pretreatment, fabrication of the metal shell, frame fabrication.

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It's not going to be a backscatter event if your ping-pong ball hits the frame or these strings, or the top part.

打到原子核了就是背散射,如果打到框上。

麻省理工公开课 - 化学原理课程节选