lovely find, nice example of Dutch misattribution. It is assumed that all modernistic looking vases found in this country are by Meydam, who is of course partly to blame for releasing a lot of "inspired" design during his days as chief designer at Leerdam.
The blue triangular vase so misunderstood is by Frantisek Vizner, made at Rosice circa 1962 (thank you Le Casson).