Place 24 cookies in the shape of a fir tree on a board. Place 3 of the biscuits in such a way that they form the base of a fir tree. Mix 200 g icing sugar and 3 tablespoons of water to a thick, sprinkly glaze.
Put 1-2 tablespoons of it in a freezer bag and cut off a small corner. Spray different sized fir trees on 21 biscuits. Stir the rest of the icing with lemon juice until spreadable. Colour the Christmas trees with it and sprinkle or decorate with colourful sugar pearls.
Decorate other biscuits as you like with liquorice, colored chocolate lentils, effervescent sweets, chocolate hearts, gummy bears, dextrose hearts or other colored sweets. Knead marzipan and 1 tablespoon of icing sugar.
Roll out on the remaining icing sugar and cut or cut out shooting star, angel and Santa Claus. Colour the remaining white icing partly red and blue and paint the marzipan figures with it.
Paint eyes, shoes and numbers on the figures and biscuits with colourful sugar writing. Stick marzipan figures with icing on the three free cookies.