Because of high customizations in the one-of-a-kind production companies (OKP companies), these companies need to find a way for reducing the production cost, shortening the production lead-time, and maintaining the quality of the productions as in the mass production system MP.s. Currently, production scheduling in OKP system follows the traditional mass production system, which focus on time and inventory, and it is inapplicable. Actually, OKP system works based on customer requirements, where each order can be representing as multi-project based. In this paper, One-of-a-kind production OKP has been referred as a project-based production and as a flexible resource- constrained project scheduling problems (FRCPSs); because in practice, some of project activities cannot be pre-determined due to its high customizations and great uncertainties. A new model has been proposed based on these assumptions to create production schedules for OKP system, which focuses on time and resources as in project management system PM. s, and deals with the problem which have three categories of project activities A, B, and C. The per-findings indicated that the model enhances the applicability of resulting schedules, emulates what a project manager in practice does (i.e. adding or removing resources from tasks to have the project completed in time), increase the number of feasible solutions, and reduces the project duration.