First, I'm new to the forum, so thanks for letting me join and post here. I hope this has some value for others.
I've been working on building this sauna tent for about a year now, and have a pretty good working model. It's a hexagonal dome, using a 240g poly fabric (for it's water repellence and flame resistance), and measuring 9.3ft corner to corner (or 8ft side to side). Can fit about 4 people including a mid-size 25L stove. https://www.instagram.com/p/CYldWHyKUD4/
I used pre-made 8.5mm x 17ft poles as the basis for the frame and built from there. A silicone baking sheet forms the chimney collar.
For those that aren't familiar, these portable tent saunas are somewhat common where I live now, in Denmark, and it keeps a respectable temperature inside for a steam sauna - 150F degrees. It could also work well as a hot tent for 1-2 people. It has an internal height of about 5 and 1/2 feet and the whole thing only weighs about 8 lbs - minus the stove.
I was inspired by the traditional American sweat lodge design - dome shaped and willow branches - to make it like this.
Anyways, I'd like to take it to market, but I think some things need refinement and I have no idea how to source competent design advice or materials, and was wondering if anyone had any advice or just thoughts in general. For example, I think there could be better fabric choices, and I think the 8.5mm poles are undersized (but am unsure if larger diameter poles will achieve the same arch shape), but would rather get some consultation before investing more in materials.