I'll pick up where I left for the oval.
* Primitive Mode
* Select your distorted circle
* Rotate [3]
* Rotate Snap (Degree) limits the angle. Select 1 (degree) for total freedom
* Note how the values in the Transformation Matrix change. That's why I scale a prim only when it is horizontal or vertical. Working on the values will distort your prim and I never managed to scale via the matrix whitout distortion. You might still scale via Scale [4] but only unifomrly.
* There is a Copy icon at the bottom of the Transformation Matrix dialog. Click it, once you're happy with the position and rotation of your white circle. This will copy the matrix to the clipboard
* Add a 4-4ndis.dat with the same center. It will be horizontal and square
* Presuming your ndis is still selected click the Paste icon in the Transformation Matrix. Your ndis should perfectly match your disc
* Join all 8 vertices of the ndis with the surrounding vertices.
* Your pattern should be ready for export.
Do some quality control:
* Edit -> Detect Triangle Overlaps
* Select BFC
* Hit Preview. Everything must be green.
w.
LEGO ergo sum