I am making a pattern currently for a new backpack and plan to add in a removable wrap-around waistbelt. I want it to use 3D spacer mesh, but I have never used this before.

The plan is to use the mesh with xpac on the back and a layer of 3/8" foam from QuestOutfitter for extra comfort. What is the best way to go about creating something like this and securing the foam into place? Thanks for the help.