I was walking down a creek on one of my neagari safaris, and I came across this portion of a hollowed tree trunk. It looks like it would make for a good base to create a penjing display. I usually see penjings on stone or rock, not anything like this. I think it would look cool, but I'm not sure how it would look natural as a small landscape, and of course I'm concerned about how I would treat it to prevent rot. I'm still learning about bonsai traditions and techniques, so any guidance would be appreciated.

I'm interested to see if anyone has any answers to your questions, as that's a beautiful piece of deadwood.

Picture made at an exhibition in Delft this year:

I would first clean it, then use a dremel or so to clean the soft parts. Then do a bit of carving, or use a steel brush to further clean and deepen the grooves.

Seems Paraloid B72 is the best wood hardener to conserve it - it's used for restauration as well. I'm going to need something like that too, but haven't found where I can buy it yet (apart from ordering it online with relatively high shipping costs. I may order it, still).

Google Paraloid + bonsai for more info.