Took out the sand form after 2 days.
The brickwork is very traditional Neapolitan, as in, it looks like I threw the bricks in from a distance.
The outer bricks I could put in place doing something that sort of looked like masonry, towards the middle the gaps got so big and irregular that I went with the slurry method. And it worked a charm, I didn't really have to hydrate the mortar that much more to be runny enough.
Things I would do different: The oven looks very small on the inside. I think I'd like a bigger one. Also, at first I wanted to do 15,5 soldier height and 15,5 arc, but when I drew it out, the arc was pretty much horizontal and it scared the %$# out of me, so I went with 13,5/17,5. But now towards the walls the ceiling seems very low, even too low to put a big log. So that might have not been a good idea. Time will tell.
Also: Next time I would put a layer of saran wrap over the newspaper. I'm having a hard time getting all the paper of, in fact, I gave up, and it will eventually burn off I guess.