Here's an interesting behavior that I haven't seen documented yet. Spoiler The left loop will stop at the pillar, but the right loop will pass through it. I ran across the behavior when I was working on a variation of mekorama level 32, The Cube. After discovering this, I started charting out flexible 3D cube mazes using graph paper, but it's been an ongoing personal challenge for months. I finally decided to make a (relatively) easy level using the same idea called strange twist. Here's what's happening, for those who have at least solved the level and want the mechanics of the example posted just above. Spoiler The base of the right loop's pillar contains a draggable block, which allows the the two (theoretically) movable structure to ignore the boundaries of each attached and movable section. The left loop only has a draggable block as part of the loop, so the boundaries of the pillar are set. I suspect that mekorama moving/movable assemblies calculate their boundaries on whether they either have firm attachment points, or have paths which cross. That would explain why the sliders in invisibl walls are able to pass through the boundaries of perpendicular sliders' rails.
One more observation: The behavior only affects two movables which are adjacent in the larger movable object. In this next example, all three sections are theoretically movable, but the two swinging arms cannot pass through each other, only through components of the central section which is adjacent to each of the arms. Spoiler
@explorer It's actually an exploit that has been discovered before by @Caken here. @meko further explored it in his level "Passing Through" and @richardfu_ made use of it in his "Glyph Walk". Lately I also used it in "The Unconscious"
@cpw - That's what happens when you get someone like me posting uncontrollably about a new toy. *laugh*
