Sorry, Daisy. There are so many ways to mount plants. Everyone seems to have their own way of doing it and generally speaking, their way works for them.
I don't using fishing line for two reasons. Mono stretches and can really put a lot of pressure on roots. Mono, unless you are using a really high quality, really expensive brand, has a memory. I find it hard tie without another set of hands to help. Also, since I drill holes through whatever wood I am using, mono is extremely hard to thread through those holes, particularly if the wood is thick.
I use gobs of Portuguese cork. I always mount on the "rough" side. It really doesn't matter which side you mount on. It just depends on how you want to present the plant. I use florist wire to tie my plants to the mounts. I actually just got in (yesterday) four spools of this wire. I have always used 24g wire but this time ordered 22g. I thought a thicker wire would have more uses. The 22g is still real thin and pliable.
I back up all my orchids with long-fibered, sphagnum moss, and if I want a bit more moisture surrounding the orchid's roots, I will front the roots with the moss as well. If I want to hide the wire (its green, as is), I will simply wrap the wire with the moss and when the wire is cinched in, the ties will be invisible.
I have never mounted an orchid using the cork slab as a "raft" but one day I will do that I just haven't gotten around to it.
The cholla wood you are referring to is absolutely nothing like the two pieces I prepared. Those two pieces are hard as a rock and preparing that wood before sealing was like dealing with hard wood, really dense hard wood. I assume the wood I got is from the base/root areas. The wood you refer to is from the branches and is very light, with lots of holes, and in cylinder form. It is used in terrarium and aquarium settings.
