New Felt Project

Kaiser, that is a very thoughtful and well done restoration - wish I had your skills! Please take note of Sandy's recommendation above re Museum grade foam used by conservation people Worldwide. As he says it is free from CFC's and so does not produce what is called 'off-gasses' which degrade objects at the cellular level. Just because you have seen no problems in the past twenty years does not mean that microscopic damage is NOT being gradually done - this is why conservation people use it, for VERY long term care of objects. Search for Plastazote, not ridiculously expensive and it comes in all sizes including the size you are using now. I have used it for over twenty years and highly recommend it for it's versatility in jobs like this.
Best regards, Steve