Here is a very good angle carpentry ... which will be used everywhere! After checking the squareness there is nothing wrong, the accuracy is at the rendezvous. There are no parasites play in assembling the two tenants. Riveting seems good also, it should not move in time. Graduations of the engravings are correct, but their depth makes me think that it will not last quite life, to be confirmed.
The only flaws: - The finish is medium at the tab, many small marks / streaks in aluminum - The 45 ° angle is not as accurate as the squareness