First soften the icing paste you need by shortly kneading it.
For the rose stem
Sculpt a bit of the paste into a "drop" shape (about 5 cm high). Narrow the belly of the drop by slightly pushing it together.
For the rose petals (4 petals per flower)
Roll the icing paste between a foil until it's 2.5 mm thick.
Press out circles of 1.5 cm.
Arrange the circles between 2 sheets of foil (not too close to each other). Flatten 2/3 of the surface of each circle by sliding over the surface with the side of a smooth scraper. Only the basis of each circle must remain a bit thicker.
Lay a rose petal on a sponge covered with plastic film. Press
your thumb on the thicker basis of the petals and press it into the
sponge to form the typical rose petal.
Fold the first rose petal completely around the top of the rose stem.
Then press the basis of a petal against the stem. Repeat with 2 more petals. The petals must slightly overlap. Gently fold open the top of the petals.
Push the base firmly together and cut away the excess paste.