Continued work on the left stabiliser skin.

First deburring all holes inside and out. Very lightly, not too much pressure and 2 turns to avoid widening the hole.

Then started dimpling the left skin.
This is how it looks like when dimples have been punched in.

Dimpled all remaining structures for the left stabilo. Found a better technique to do this using the hand squeezer. I now put the hand squeezer with the forward arm down on the table, longeron perpendicular with the work bench.
Then slide the piece to dimple in and squeeze it using full body weight. It is less tiring then trying the squeeze with hands and it creates nicer dimples.

Below, you can see the difference between dimpled and not dimpled. The left flange is dimpled, the right side is still untreated.