Pier used different techniques:
- painting (oil paint, gouache, watercolour)
- graphics (woodcut or cut in hardboard, etching)
- drawing (conté with charcoal, pencil, rotring pen)
- textile (appliqué)
From the 1980s onwards, Pier almost exclusively painted watercolour. Pier often illustrated his letters with drawings.
Several elements recur regularly:
- the (almost) white surface: silence, the (almost) nothing
- red dot: creativity; blue dot: depression, blues
- desert: emptiness
- figures: extra large or small (Quo vadis, little man?)
- labyrinth, as a circle or as a square
- Buddhist and Hindu symbols; geometrical symbols