It you haven't already got them all the attachments for a Fein Multi tool, the rubber shaped sanding blocks to get into chamfered T&G is a life saver, Multi hole sanding attachment with Abranet discs are amazing for the lack of dust when attached to a shop vac.
A roofing square used mine so much I bought two other size's.
A roofing square used mine so much I bought two other size's.