This is easily done with a white wax crayon.
Draw your design on the white egg. When its dipped in
the hot blue dye, everything turns blue except your design.
I was telling someone today about my childhood memories of Easter.
I still can’t smell vinegar without recalling dyeing eggs with my Granny.
(Someone on the radio today called the coming week ‘Traditional Egg Salad Week’.
That was definitely true in our house - though we ate a lot of them just plain, too; or sliced with a special egg slicer for sandwiches. I think the week after Easter was almost the only time that slicer was used - but I still keep one in the small gadget drawer, for old time’s sake :-)