Outstanding

Greetings all! I am a nube to both SU and woodworking. The attached .skp is my mental gap. I am trying to miter the drawer sides and back. A 45 deg. face extruded from the top face down will go through the top ell. I can force it to go to the dado's top face. After that, I get all sorts of issues. Somehow I managed to get the dull gold member done. It was a chore. My design process was to create the extrude profile first then miter it, even though, in the shop, I would put the dado in after the miter operation.
Thanks for any input!!

10 drawer utility box.skp