Hard boil eggs. Or for hollow eggs:
Wash eggs. With a large sewing needle, trussing needle or ice pick, begin by pricking small holes in both ends of each raw egg (use week old eggs if possible, as the yolks won’t be as firm). Gently push the needle through into the cavity of the egg to break the yolk membrane several times. Blow into one hole, either using your mouth or an egg blower, until the contents come out the other end. When the shell is empty, gently wash and dry, making sure that all water has drained out of the shell.
For each colour, place 1 cup of water plus 1 tbs vinegar in a bowl that will allow the egg to be at least mostly covered. Stir in several drops of food colouring, depending on the intensity of the colour you want. Using a spoon, lower each egg into the dye. The hollow eggs may not fully submerge, so turn over in the dye for even coverage. Remove from dye, making sure that hollow eggs have drained completely.
To Tye Dye, very carefully wrap eggs in rubber bands before dying. The dye won’t colour where the bands are. Remove the bands and place in a second colour, if desired. Or draw on eggs with wax crayons before dying. The dye won’t affect the crayoned areas.