How well-studied is origami field theory?

There is a paper posted on ArXiv by Antonio M. Oller Marcén entitled "Origami Constructions" that claims to show that:

If $a \in \mathbb{R}$ is origami-constructible, then $$[\mathbb{Q}(a): \mathbb{Q}] = 2^r3^s$$ for some $0\leq r, s \in \mathbb{Z}$.

Unfortunately, I have not been able to find this particular paper published in any peer-reviewed venue nor am I able to personally vouch for the proof, so I guess caveat lector.

EDITED TO ADD:

The same result is also found in a Master's thesis by Hwa Young Lee entitled "Origami-Constructible Numbers" (Corollary 4.3.10, pg. 50).