This seems pretty straightforward. I did it on a simple 10” square block to generalize.
Then I slid a copy of the block 5” (halfway); subtracted one half from the other. Rinse and repeat.
Then I shelled out both now 1/2 sized blocks.
Ignore the construction plane, I ended up not using it.
Then I did a 0.05” inset from the inside of the shell, then another 0.125 and extruded 1” for the joggle/doubler. The 0.05 inset could be considered space for glue. Because it was hanging on the edge of the shell, I used the Transform tool to push it back 1/2 “.
And that’s it. One half slides into the other. With regard to the joggle, I could have alternatively done an outset of 0.05 “ and then slid it back and done a Union to its half. But I like to keep parts separate until I know my approach works.
Actually doing the post took much longer than doing the model! The forum editor does not adapt well to my 11” iPad Pro size.
And this is my good deed on this rainy day…