Very course bark, but put the roots (if any) on top of the bark not in it (use a stick for support), in a clear pot or basket, mist them and hope some root buds grow out and climb into the bark
keep in a clear plastice bag and put the cutting on top of moist moss until the new roots come out. You can dip the cutting in 'roots stimulator' for faster growth.
Yeah roots stimulator work on Vandacae cutting. Use the gel type as i find it easier to managed. You might have to apply it more than a few time to thou. I'm still testing with my vandas. Some of my renanthera shoot out crazy roots, while other not so much. But its the best solution, outside of growing in the tropic thou.