rotate(ArmsOnEdges ? 180/NoArm : 0) // Rotate the polygon to it's 

The issue here doesn't appear to be the rotation itself, but the position of the cubes. A cube is created with it's lower-left corner at the origin: When this is rotated, the corner is rotated, and when you have several of them, it looks "twisted." What you probably want is to center the cube on the X axis only. Currently, this must be done by manually translating the object by half that dimension. In addition, you're having it extend along the Y axis. To line it up with the circle polygon, it'll be easier if you extend it along the X axis. To create the center polygon, you can use a cylinder with the $fn parameter to control the number of sides. All put together, you get something like this: And here's the updated code, with comments, for your modification. NoArm = 7; // The number of arms / sides of the polygon ArmWide = 3; // The width (short side) of the arms ArmHigh = 3; // The height (along the Z axis) of the arms ArmLong = 80; // The radial length of the arms ArmsOnEdges = true; // Should the arms intersect the edge or vertices of the polygon CircRadius = 30; // The radius of the polygon union() // Union isn't strictly necessary because everything at the top level is implicitly unioned { for (i=[1:NoArm]) rotate([0,0,360/NoArm*i]) // Rotate the arm after it's centered translate([0,-ArmWide/2,0]) // Center the arm around the X axis cube([ArmLong, ArmWide, ArmHigh]); // Make the arm extend along the X axis rotate(ArmsOnEdges ? 180/NoArm : 0) // Rotate the polygon to it's side if so desired cylinder(h=ArmHigh, r=CircRadius, $fn=NoArm); // The polygon, as a cylinder with a particular number of sides } Best, ~ Yona