I don't think there is a way. Are you painting one of those toothpick beam sabers?
I had been in the habit of painting them with a custom mix of pink or green (whatever color it's supposed to be) usually I'll paint it a little darker at the base by the handle, make it lighter in the middle, and then darker at the tip. Hope that helps... unless you're not painting beam sabers

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Until Next Time: Happy Building!
-Joe
Joe's GunplaWant to Buy LM Leo or Taurus from Gundam Wing, built or unbuilt! Willing to pay big!