The warhead used enriched uranium (code named oralloy) as its nuclear fissile material and could be used in two different yield configurations.

This required the assembly and insertion of different pits, with the amount of fissile materials used controlling whether the destructive yield was low or high.

[4] The initial army designation for the weapon was Shell, AE, 8-inch, T317 and the Atomic Energy Commission (AEC) nomenclature was Mark 33.

[4] The design remained in the research and development phase until funds were assigned to the project in February 1954.

Judging by the remaining photographic evidence, it is likely that the exterior casing of the artillery shell itself was made of titanium.

[6] The W33 mechanism has been reported to have comprised two critical nuclear parts which were required to assemble a complete W33 warhead.

Plumbbob Laplace was test fired with the device hanging from a balloon at an altitude of 230 metres (750 ft).