The prim in the bottom left-hand corner is all distorted.
* Delete that prim
* Select the disc in the bottom right-hand corner:
1 0 17.5 0 -17.5 1.5 0 0 0 1 0 0 0 -1.5 1-4disc.dat
* Copy and paste
* To distinguish it from the original prim color it
* Manipulating the matrix it will be mirrored and moved to -X
* Furthermore change 1-4disc.dat to 1-4chrd.dat. A chord requires less room as I told you above.
1 14 -17.5 0 -17.5 -1.5 0 0 0 1 0 0 0 -1.5 1-4chrd.dat
Compare the two codes and read my tutorial at:
http://www.holly-wood.it/ldraw/authoring-en.html
to get a least a bit of an insight
* Color your chord
* There will be room left by the deleted disc prim
* Click Create a new quad (7)
* Make sure you have selected "Black" in the color bar of the 3D editor
* Select the four vertices to create a quad
* It is not important to respect a clockwise or counterclockwise order or go for a bowtie. LDPE will do all the magic for you
* Your quad will be place at the very bottom of the text editor and should have this figures:
4 0 -17.5 0 -18 -19 0 -17 -19 0 -17.5 -17.5 0 -19
Screenshot
LEGO ergo sum