dec. 1965: wooden cubes arranged with decreasing density of the elements from inside to outside; titled 'toevals-objectivering', signed, dated '16-22 december 1965', dedication '→ dw van krevelen, arnhem' and inscribed with the program 'met van binnen naar buiten afnemende dichtheid van de elementen' on the reverse (felt pen)
1966/11: wooden squares arranged in a 15 × 15 grid pattern with at random choice to place the element or not; titled 'toevals-objectivering', signed and dated/work number '1966/11' on the reverse (felt pen)
1966/12: plywood elements (lengthwise slats of 2.3 × 1.3. cm, 1.2 cm apart) horizontally arranged with at random choice to apply the element (for even numbers) or leave out line element (for odd numbers); titled 'toevals objectivering', signed, dated/work number '1966/12' on the reverse (felt pen)
1966/13: plywood elements (10 × 10 × 1 cm) arranged with at random selection of place and number (overlap allowed); titled 'toevals-objectivering', signed, dated/work number '1966/13' on the reverse (felt pen)
1966/14: plywood elements (1 × 2 × 2 cm) arranged inside the squares of a 19 × 17 grid pattern (4 × 4 cm) with at random selection of direction (horizontal-vertical); titled 'toevals-objectivering', signed, dated/work number '1966/14' on the reverse (felt pen)
1966/18: wooden blocks of different sizes, 7 of each size, arranged at random; titled 'toevals-objectivering', signed, dated/work number '1966/18' on the reverse (felt pen)
1966/19: random number of wooden slats (15 mm thick with lengths in multiples of 15 mm, up to 16.5 cm long) arranged with at random selection of place and direction (horizontal/vertical); titled 'toevals-programmering', signed, dated/work number '1966 / 1966/19' and annotated 'voor de collectie d.w. van krevelen' on the reverse (felt pen)