Don't do what I did. On the DE spars I used 3/4 x 3/8 sticks for the ribs to be secured do. AFTERWARDS when putting in the lower diagonals discovered to my chagrin that the GUSSETS for those diagonals had to be reshaped to accomodate the larger size. Boy, the guys on here who say READ AND STUDY the plans, well, let's say I learned the hard way.