The mRNA delivery vehicle technology is one of the key factors in developing mRNA-based therapeutics and vaccines. The delivery vehicle must protect the mRNA from degradation, accurately deliver it across body barriers into the target tissue or cell, and properly regulate expression of the protein. Even though the stability and performance of mRNA delivery vehicles is highly dependent on their nanostructure, most vehicles were irregular spherical shapes. In this chapter, we describe a detailed protocol for fabricating nanotubular mRNA delivery vehicles using self-assembling peptide building blocks. We present design principles of the peptide building blocks and formulation strategies of mRNA–peptide complexes. Additionally, we cover methods for characterizing and assessing their thermodynamic stability and intracellular performance. These protocols should help facilitate the development of precisely structure-controlled mRNA delivery vehicles.