The next release...which we are all wating on!While not necessary for physical simulation, its a visual detail aspect that some will find helpful in the design phase.
"Blueprinting" and aesthetics is another aspect of rocket design that OR is used for.
Not possible with the current release to have transparency, you could color it a light blue or something.
AFAIK, true clear/semitransparent parts should be in the next release.
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