He im in the middle of a respray and the best tool for sanding is a cp air random orbital palm sander. I am using 320 grit and did one side of my sprinter in under an hour. There is not a single swirl mark and it comes out smooooooooth. Very much worth the price. Prep work is everything. paint isnet very thick and dosent hide anything underneath. Make sure you use the same brand for primer and colour and clear if needed.