Though gestures can convey the meaning of the message and the thoughts of the speakers, there are limited research studies on how co-speech gestures are used in presenting engineering-related messages. This case study aims to understand how four types of gestures (beat, deictic, iconic, and metaphoric) are used in engineering proposal presentations to convey technical solutions in proposed products. This study employed a mixed-method research approach of using both multimodal discourse analysis and quantitative analysis to examine the ways two student presenters used co-speech gestures to communicate technical solutions in engineering proposal presentations. The findings showed that iconic gestures were used most frequently by one presenter to mimic the visual representations of designs and processes in engineering systems, co-occurring with spoken language to reinforce the propositional content. Deictic gestures were used most frequently by another presenter in directing the audience's attention to visual figures to facilitate the explanation of technical content. In comparison, beat and metaphoric gestures were used less frequently. This case study informs multimodal research on ESP spoken discourse and provides pedagogical implications for the application of gestures to facilitate the communication of technical content and concepts in engineering presentations.