Whether you're making sugar eggs to hang as ornaments, to hollow for treats, or to decorate with a holiday theme, the technique is essentially the same. Humidity affects how well the sugar will set and thus how long you'll need to wait to apply royal icing (to join your eggs together or to decorate); if possible, make this project on a dry day. Use stiff royal icing to glue pieces together and to pipe decorations, such as flowers and bows. Medium-stiff royal icing is good for beading and piping lines and designs.
If they are packed properly, sugar eggs can last for years. To preserve them for many Easters to come, wrap them in plastic to keep out pests, put them in boxes nestled in light padding, and store them in a dark, dry area.
There are three ingredients in the sugar mixture: superfine sugar (also called bar sugar), which gives a smooth texture and sparkle to finished eggs; water; and liquid or gel food coloring. Place two 1-pound boxes superfine sugar (about 4 1/2 cups) in a mixing bowl, and add 3 tablespoons water. Use your hands to work water into sugar thoroughly. Mix in tiny drops of coloring until you've reached desired shade. One batch yields one large egg (about 6 inches from top to bottom) or several smaller eggs. To keep bowl of sugar from drying out while you're working, cover it loosely with a damp paper towel.
Pack the sugar mixture firmly into plastic candy molds. Pack a large mold in layers, firming the sugar before adding more. Some egg molds have two identical halves; others have one flat side upon which the egg will sit.
Invert the molded sugar onto a cardboard cake round or baking sheet. If it breaks apart or any cracks appear on the surface, repack, and try again. For a view egg, cut out an egg-shaped paper pattern of the window size you want, place it on the egg, and outline it with a toothpick. You can also use an oval-shape cookie cutter as your guide. Scrape out a little of the sugar from the window area, leaving loose sugar on the surface; this keeps the top from becoming too hard to break through. Set aside to dry for about 3 hours.
Hold the egg half gently, and hollow it out with a melon baller or small spoon; keep a 1/2-inch border. For a view egg, start with the window. For larger eggs, the walls should be about 1/2 inch thick; smaller eggs, 1/4 inch. The sugar that you scoop out can be reused for another egg as long as you remove the hard bits. Inevitably, some eggs will break as you're working with them, so it's a good idea to make an extra half. Set aside to dry for about 2 hours.
To smooth the rough edges and help join the egg halves neatly, rub the egg in a circular motion over sandpaper that has been placed in a baking pan to catch the sugar shavings. You can also use sandpaper to smooth opening of a view egg or to make a flat bottom so an egg can stand without toppling (if you plan to do this, leave the bottom a little thicker when hollowing out the egg).
To decorate the inside of the view egg, place a piece of gum paste -- a malleable, edible substance, available at baking-supply stores -- on the base of the egg half without the window. Secure your ornament inside (bunny, flower, etc.). You can also use gum paste to form almost any decoration. To make dogwood blossoms, for example, use a pastry brush to dust a smooth work surface with cornstarch, then roll out gum paste into a paper-thin layer. Cut it with a dogwood-shaped cutter. Place the flower shape on foam pad; use a balling tool to shape petals. Let flower dry on parchment; brush on powdered colors (see Sugaring).
To join halves, pipe royal icing onto one, and press another against it. Hold in place for a few seconds; let dry 1 hour. For egg ornaments, knot a piece of ribbon at its midpoint, and lay onto royal icing with the knot just inside one half of the egg and both ends of ribbon sticking out. Dot royal icing onto the ribbon where the other half will join; press egg half into place. Let dry. Tie ribbon ends into a small bow or knot.
Glue superfine sugar to egg surface with an egg-white-and-water mixture. Dab powdered coloring into sugar to color it, or leave it plain. Then combine two egg whites with a few drops of water; beat with a fork until frothy. Working with half an egg at a time, paint whites onto egg with a soft paintbrush. Spoon sugar over wet egg whites, and gently shake off excess sugar. For plaid eggs, make stripes in one direction, and sugar them. Let dry, about 15 minutes. Then make stripes in the other direction, painting over the first stripes. Hold finished half against other half; in order for design to match up, pipe dots of royal icing onto second half to mark where stripes begin.
This technique incorporates royal icing and sanding sugar, which has a slightly larger, crystalline grain. The icing can be tinted with liquid colors, the sugar with powdered coloring, or they can be left plain. Use a small round tip (#1 or #2) to pipe medium-stiff royal icing onto an egg, then spoon the sugar over it. Let dry; brush off excess.
Different techniques create different flowers. To make a daffodil, pipe onto a flower nail using a small rose tip (#101); pinch the petals at the ends (dip your fingers in cornstarch first) for a daffodil shape. Let it dry. Use a #1 tip to pipe the flower centers. For the stem, insert the tip of a cloth-covered wire into a #2 or #3 round tip, and squeeze the bag, forcing wire out and coating tip in icing. Adhere this to back of flower. For the leaves, insert a piece of curved wire into a leaf tip (#352), and pipe it out; the wire will be at center of leaf. For lilies of the valley, pipe with #80 tip directly onto a wire. The large green leaves are store-bought. Anchor leaves and flowers in gum paste.
To crystallize edible flowers, thin an egg white or powdered egg whites with a bit of water. Hold the stem with your fingers or tweezers; coat with egg white using a small paintbrush, and sprinkle with superfine sugar. Put flower on a tray covered with waxed paper; set in a warm, dry place to let dry.