It is proposed that by using computing analysis software and 3D fabrication techniques, low cost plastic trumpet bells could be produced for different music genres by altering their timbres. These may be attached to the trumpet in a similar manner to that of a tuning bell trumpet. The novel bells are designed to eliminate or enhance particular harmonics to change their brightness by altering the thickness of material, thus altering the impact of the vibrations to the sound column within it. This initial paper focuses on a comparison between the natural resonances of a current trumpet brass bell and various modified plastic bells using simulation software. Various designs are presented that show the resulting changes of the resonance harmonic mode frequencies and deformation amplitudes for Acrylonitrile butadiene styrene (ABS) can be shifted toward that of brass depending on the thickness of the material thus paving the way for designed plastic trumpet bells with similar tones.