This paper presents a method for selectively removing carbon shells from multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotube (SWNT) ropes to tailor their electronic properties. The technique uses current-induced electrical breakdown to remove shells one at a time, allowing for the conversion of MWNTs into either metallic or semiconducting conductors. For SWNT ropes, this method enables the generation of arrays of nanoscale field-effect transistors (FETs) based on the fraction of semiconducting SWNTs. The process allows for the characterization of individual shells and provides insights into the complex electronic structure and transport properties of these nanotubes. By selectively removing shells, the method enables the separation of semiconducting SWNTs from mixtures and the fabrication of nanotube-based FETs. The technique has been demonstrated on various nanotube systems, including MWNTs and SWNT ropes, and has shown the ability to control the electronic behavior of these materials. The method also allows for the study of the electronic band gaps of different shells and the transport properties of nanotube bundles. The results indicate that the controlled breakdown technique is a valuable tool for both the study of nanotube interactions and the fabrication of nanotube-based electronic devices. The technique has been applied to create arrays of independently addressable SWNT FETs, demonstrating its potential for practical applications in nanoelectronics. The study highlights the importance of controlling nanotube reactivity and the potential of this method for advancing nanotechnology.This paper presents a method for selectively removing carbon shells from multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotube (SWNT) ropes to tailor their electronic properties. The technique uses current-induced electrical breakdown to remove shells one at a time, allowing for the conversion of MWNTs into either metallic or semiconducting conductors. For SWNT ropes, this method enables the generation of arrays of nanoscale field-effect transistors (FETs) based on the fraction of semiconducting SWNTs. The process allows for the characterization of individual shells and provides insights into the complex electronic structure and transport properties of these nanotubes. By selectively removing shells, the method enables the separation of semiconducting SWNTs from mixtures and the fabrication of nanotube-based FETs. The technique has been demonstrated on various nanotube systems, including MWNTs and SWNT ropes, and has shown the ability to control the electronic behavior of these materials. The method also allows for the study of the electronic band gaps of different shells and the transport properties of nanotube bundles. The results indicate that the controlled breakdown technique is a valuable tool for both the study of nanotube interactions and the fabrication of nanotube-based electronic devices. The technique has been applied to create arrays of independently addressable SWNT FETs, demonstrating its potential for practical applications in nanoelectronics. The study highlights the importance of controlling nanotube reactivity and the potential of this method for advancing nanotechnology.