That does look like a fun project.
Any way to make it into a selfbondage toy?
I wished we could get I photo of the back side.
That would answer a lot of my questions.
After studying the picture, very closely, it can not be used for self bondage for a number of reasions.
First of all, the harness around the subject can not be fully tighten, as two of the straps looks to be around the H-frame. Also, the ice locks would add bulk to the H-frame. Magnetic locks may work, if they were small and very strong.
The H-frame looks to have six main wood parts. The basic H uses three peices of wood. The neck assembly uses 2 more and the last peice of wood that you can't see, fits to the waist.
The chain shown is not part of the frame that I can see, but is an afterthought and is put to good use.
Therefore, this setup as shown can not be used for selfbondage.
However a self bondage version can be built. But pretty much the whole thing would need to be somewhat custom.
Way too devious, I should say...