The Tweaker draws closer to completion. Knocked a little test apparatus together that shows accuracy relative to indentations of +-1 degree. After some design revisions it now has a centre laser, a 1.5mm black anodised front plate for durability and is now USB-C rechargeable with an expected 12.5 hour battery life!
Improvements to the Tweaker prototype now mean it now passes the test known as "the JBL Control 1 benchmark". Logic being that if it sticks to the grille of one of these it'll stick to anything.