Jonna, it's a conglomeration.
Down the middle of the pot I have a piece of plastic tubing, which is what my landscape plotter paper comes on.
Big paper rolls either 24" or 36" wide. I save the tubes and reuse them to mail landscape plans.
Then I had the idea of planting my orchids in the strawberry pots I found at a yardsale.
I knew the middle would get soggy and never dry out. So I sawed off a piece of the plastic tube and used it for filler in the middle.
Then I used 2-3" of packing peanuts on the bottom of the pot and inside the tube, then plain old orchid chips and then around the holes where I stuck the orchids,
I used coconut fiber torn from a coconut planter liner to keep the plant and chips in the pot, stuffing it gently around the orchids as I put them in the holes.
There are 5 orchids crammed in the top and one of those tropical ferns that came up as a volunteer in one of my other pots.
Not even 2 weeks after I planted them, I noticed phenomenal root growth.
Many orchids naturally grow perpendicularly from tree trunks and branches,
so I think growing them at this angle stimulates root growth. And when you have good root growth...very soon after you will have new leaves and spikes.
Now mine has a bunch of new growth and ever single orchid has a spike. And the roots are growing over the outside of the pot, as if hugging a tree trunk.
Also, orchids need a LOT more light than most people think.
These orchids get very bright light all day and late afternoon sun, just before sunset.
Good ventilation is a must.
If you grow them on slab/wood, I would suggest covering the slab with moss first, or coco fiber.
I use thin rubber bands to get them to cling at first. By the time they attach by themselves, the rubberband falls apart.
I think on bare wood it's just too dry for them.
They grow on mossy trees in their natural habitat.