Have your forcers ready for making the decorations

From 1922:

Ingredients: Five cups of flour, three cups sugar, 1 ½ lb. butter, twelve eggs, two cups currants, 1 lb. mixed peel (cut into shreds), one dessertspoonful salt, one teaspoonful baking powder, ½ lb almonds (blanched and pounded), ½ oz. grated nutmeg, ½ oz. ground cinnamon half a pint brandy.
Mode: Beat the butter to a cream, gradually beat in the sugar, add the frothed whites of the eggs, beating well all the time, then the yolks. Now by degrees add the flour, salt, powder and spices, mixed together; then the currants and peel, and after more working, the brandy. Be sure your ingredient are all well beaten and well mixed – mix and mix again. Bake in a moderate oven about three hours.
Icing the Cake.
In the instructions for icing a wedding cake, reference is made to a “forcer.” A forcer is an apparatus with a metal nozzle and a soft bag into which some of the icing material is put; By squeezing the bag, the icing material is forced through the nozzle and can be manipulated into fancy shapes, such as are seen on cakes. A makeshift forcer could be made by taking the clean nozzle of an oil can, cutting off the end until the opening is of the right thickness, say, the size of a small straw, and fastening a bag of close calico on to the nozzle. When the nozzle chokes one way of fixing it up is to poke a skewer or wire up it. Another which I saw a confectioner adopt was to suck it or blow up it. The people who were to eat the cake were not present.
Icing for a Wedding or Birthday Cake Ingredients: 3 lb. of icing sugar, 1 lb sweet almonds, whites of five large eggs.
Mode: For the almond icing, which lies next the cake, take the almonds, blanch them, and throw into cold water for one hour. Then put them into a mortar and pound them to a smooth paste, adding a few drops of water now and again. When well pounded add 1 lb. of icing sugar and mix well. The preparation is now ready for the cake. Place your cake upsidedown on the back of a large plate. If not level pare a little off the top of the cake. If the cake is greasy, dust on a little flour and wipe off lightly with a cloth. Now place your almond icing on the cake with your hand, smoothing with a knife dipped frequently in cold water. Do not use too much water, or the icing will take longer to dry. Make this icing about half an inch thick. Leave it two days to dry, then it is ready for the sugar icing.
To make sugar icing put 2 lb. of icing sugar (no other will do) into a basin, throw in the whites of the eggs one at a time. The whites should not be whisked, only beaten a little to break them; also take care not a speck of yellow goes with the white. Use as few whites as possible. The number will depend on the size. Three should be about sufficient for 2 lb. of sugar. Work the first white of egg well into the sugar with a spoon, adding a few drops of lemon juice now and then. When it has been worked for a good while add another white, and so on. Add eggs until all the sugar is worked in. To test it put some on a piece of dry bread, and if it does not run it is a sign it is ready. Keep out a spoonful or two if you desire decorations. Next plate the rest of the mixture on top of the almond icing, using the blade of a knife dipped frequently in cold water to make it smooth. The icing should be allowed to harden before decorating. The cake may be placed in a cool oven or warm room for a short time.
Have your forcers ready for making the decorations. They may either be bought or a baker may lend them. You must have them if you want to decorate the cake with knobs and wavy lines. Moisten the icing with a little more white of egg before using. Ornaments, flowers, and silver leaves may be bought off any baker. If the cake is a birthday one you may sprinkle it over with hundreds of thousands of sprinkles, or use a very little cochineal to colour with according to taste. The almond icing may be omitted if preferred.