"Pink Stuff" is BOG, Process goes something like this: 1. Mark out where the box is to be installed (I just used the old 5/8ths rule of thumb, then used a 10" box to give plently of options. 2. Route out the required space to place a higher density foam into. 3. Use Araldyte or similar to coat the polystyrene foam to create a bonding surface. 4. Set the high density foam into the hole using builders bog. 5. sand flat 6. route out space for mast box/fin box. 7. Fibrglass the box in. 8. Fibreglass over top. 9. Sand Flat 10. New Grip