.020"/" is what is typically used for acetal. What type of press will this be going into? I had seen on another forum that you were using some what of a benchtop machine, is that still the case? I ask be cause I wonder about the ability of a benchtop machine being able to fully fill and pack out the part without defects as it is a pretty thick part you have there. Is the part allow for you to core it out and then add ribbing to strengthen it back up? Otherwise with such a thick part you should make a dummy cavity and measure the result for shrinkage