I bought a real birch tree trunk for visual reference at a local floral design supply in the flower district downtown. To tell you the truth, it looked as though it had a quick sloppy sponged white paint job on it. It looked good but so easy to replicate for the many trucks I'd need to finish the set.
As I started to test making a few out of the tons of free fabric core tubes I had here, I soon realized how insanely complex real tree texture really is.
Making the straight tubes (upper left) zig and zag slightly was the easy part. I used a Japanese pull saw to gouge out small 1/2" HA! wedge shaped sections for the tubes set up between two cinder blocks (center top). Then I forced the tube to collapse at the break point and used my favorite material, masking tape, to tightly wrap the joins. I also added rolled up paper clumps to act as quick branch stubs here and there.
I slathered the armatures with my other favorite material, flexible cement, up and down with a small plastic card to obscure the joins and add bark-like texture, not birch bark texture, but a generic tree impression.
Once dry, the painting tests began and what I thought would be too easy ended up being too hard.
I kept trying to get a decent Faux Bois finish on these tests, going dark light in various browns, taupes, creams, yellow, everything. I simply couldn't get anywhere. Finally, I turned off all the lights at night and took straight white and sponged it on trying to get the values right to my eye in the dark. In the morning the value was better and then it was a simple matter of tinting them over the top with dilute cocoa brown fabric dye mixed with dilute yellow acrylic to stain them for hue. They aren't Birches, but detailed enough to give the feeling of tree trunks to cover the support column on the set.
Here I've quickly hung a panel of sky-blue plastic tablecloth to start to cover the column. I propped the test trunks in front of that and then placed a piece of sheer silk in front of my camera lens on that side to softly blur. Just trying to get an idea of what needs to be done to finish off the background edges of the set.