If I'm in a hurry and need a lot of chipboard dies cut from one piece I use my xyron 900 for a perfect coat. If I am just covering a small area of chipboard with pp I use my atg
Edited to answer the op's question!!
I use a sanding set I believe was / is sold by basic gray that has some small round sanders in it (for tiny spots) and I too use the SU fine grit sanding block for edges.