bppR = [ bppN[0] + lid_buttoncover_gap, -button_cutout_depth ];
bppS = [ epp1[0], bppR[1] ];
bppQ = [ bppM[0], bppR[1] - lid_buttoncover_overlap ];
bppR = [ bppN[0] + lid_buttoncover_gap, -button_cutout_depth ];
bppS = [ epp1[0], bppR[1] ];
bppQ = [ bppM[0], bppR[1] - lid_buttoncover_overlap ];