They are installed, so no picture, but think of a D with the bottom edge bent 90 degrees. I traced the tongue onto a piece of 0.025" aluminum and added enough at the bottom to bend 90 degrees so that when I cut it out and made the bend I had a shim that covered the forward face of the forward stub spar and the straight portion of the bottom of the tongue. I did not add any shim to the curved edge, and I did not shim the rear spar tongue.
The reason I shimmed the front tongue was I noticed a click when I boarded as my weight went onto the wing. I also noticed about 3/32-1/8" play at the wing tip. The shims got rid of both.