In this paper, sizing of the thickness of a cylindrical shell subject to a stochastic force is considered. The variational principle of stochastic partial differential equations (PDEs) is applied to derive the necessary optimality conditions. The goal is to determine the optimal thickness of a cylindrical shell such that subject to a stochastic force it does not deform, although, because of the elasticity of a cylindrical shell, occasionally small deformations that do not destroy the structure are allowable. The sizing problem under a stochastic force is considered via a one-dimensional stochastic PDE-constrained optimization problem. Test examples are solved using a self-adjoint gradient algorithm.