Are there more home made float tanks than manufactured float tanks in North America?

I dont know.

Why do people choose to build rather than buy a float tank?

I am building a tank so that others can do so from inexpensive, off-the-shelf parts and freely available construction plans. I also hope to do some prison outreach at some point and low cost of manufacturing will be a must.

Do you think building your own is of the journey/fun?

In a way it is, but the real pioneering work was done by Lilly. I mean, he started with submersion and oxygen masks and evolved it to use Epsom salts. I would say that everything since then is just imitating his model. He did all the hard work.

And of course, beyond his actual construction, the very interest in answering a research question led to the idea in the first place.

I do think Ocean Front Floatation is certainly doing some impressive evolutions of the idea of floatation. But of course, most of the work is done by our Inner Intelligence anyway.