Drillstring design is essential to the success of a drilling operation. To hit a given target, the drillstring must be able to withstand all possible loads or forces anticipated to occur during the drilling operations. Failure of any of its components will results in high wellbore restoration cost. Selection of drillstring for a given field is therefore optimised by the selection of appropriate grade of pipes, outer and inner diameter, nominal weight per foot, adequate yield and tensile strength to give the best performance in a drilling operation. The selection of these parameters manually can be very challenging and where software packages are available may be relatively expensive and limited in some applications. This work therefore seeks to develop a mathematical model that can simulate and predict recommended drillstring design boundaries for a given drillstring dimensions, well trajectory and drilling parameters to select the best drillstring design for a given drilling operation using Python programming language. Drillstring specification data from API RP 7G was used to create a database for drillstring specification. Sets of correlations from SPE papers and other literature were used to create mathematical models to design the drillstring. Three mathematical models were developed; trajectory model, drillstring specification model and algorithm model for simulation and analysis of the drillstring. The programme automatically generates two additional (upper and lower designs of the input design parameters) for comparison purposes. The rating of performances of each designed model is scored against some testing criteria like collapse, tension, torsion, torque, pipe stretch, critical buckling force and critical RPM.