Couldn't agree more that experimentation is the mother of progress...and half the fun of building these things is trying things out and learning...props for thinking outside the box. I do have to second Als suggestion to keep a fire extinguisher handy...if your core is insulated well enough, it's probably only a matter of time until that OSB dries out enough to catch fire...and since it would be inside the exhaust you probably wouldn't even know it until it was falling apart (and on fire). Years ago when I was an HVAC tech, I saw some installs that did work fine for a while, but were time bombs. Things like people putting tile up behind a
wood stove and ignoring the clearances listed by the manufacturer...looks and works fine, but they couldn't see the wood behind the tile slowly pyrolizing from the heat. Another time I had a huge shop building so full of smoke we all thought the building was on fire...but it was actually the
wood stove back drafting because the chimney they put in wasn't tall enough for the conditions they had. If that had been a residence and it happened when the people were asleep, they'd be dead from the smoke and CO. I'd hate to see anyone on this forum (or anywhere else) get hurt because of their
rocket stove. There's no reason you can't do a build on the cheap and still meet basic safety requirements...my entire heater was built with stuff sourced from Craigslist and used building material stores (or stuff I fabricated from used parts). Only new stuff I bought was fireclay, perlite, furnace cement, and some consumables like welding wire and cutoff disks. Saved hundreds.
Anyway, best of luck, and stay safe. Don't be a marshmallow...or a
newspaper headline.