Photoshop :: Making Realistic Foam From Photo

I've been taking and prepping photos of a client's parts.  For the most part things have been going fine.  I use pen tool for thought - but round or curved - objects and for other objects I have a series of auto actions that clean them up quite nicely and quickly.  For example see before and after below of an object I did.  Photos were taken with Nikon D70:
 
I've now run into a really tough one and it's foam.  I told my wife to take photos of them with black background so it's more contrasty.  But I just can't seem to figure out how to get rid of the black so the result looks "foamy."  Evidently, the pen tool just won't work because lines there are two straight.  Below is example of photo and I now have about 6 photos similar with more to come.  The photo below is reduced version to keep the file size here small: