TouchSynth is a modular synthesizer project, produced for the OSU EECS captone series. A modular synthesizer is a musical instrument that synthesizes audio using discrete modules with individual functions that can be manipulated, rearranged, replaced, and customized by the user. The flagship feature of the Touchsynth is the ability for users to create unique sounds by drawing waveforms on a touchscreen. These waveforms are synthesized digitally, mapped to a keyboard, and processed through analog modules. This mixed-signal, modular architecture provides users the ability to create unique sounds without sacrificing audio fidelity, a common drawback of fully digital synthesis architectures. The device is aimed at musicians and synthesizer users who seek creative sound design, more control over their audio production, or an inventive way to interact with musical hardware. The team behind the TouchSynth is composed of musicians who share these goals of artistic expression, not only through music creation, but also through electrical engineering and design. The largest challenge of the project was the Digitally Controlled Oscillator (DCO). The touchscreen interface of the DCO required intensive testing and adjusting to maintain responsiveness while generating consistent and accurate oscillator output. The team is proud to have overcome this challenge, and the final TouchSynth system is stable and responsive with excellent performance and audio quality. While the outcome of the TouchSynth exceeded team expectations, future areas of exploration include an upgraded touchscreen, improving gate and trigger shaping, an updated subtraction circuit in the VCF, and incorporating higher quality timers into the ADSR.