Adjusted location of Plexi on frame and drilled plexi to frame per plans. Used Spruce plexi 1/8" drill through plexi (light pressure) then carefully finished with standard drill thru steel. NO CRACKS! Controlled temperature between 77F and 80F to minimize stress from differential expansion (80 degrees +-50 degrees for 30 F to 130 F service range). Test fit on fuselage - looks good.