Multiwall carbon nanotubes (MWNTs) are one of natural nano-size bricks. The MWNTs are conductive narrow wires, and would be useful materials for a component of nano-electronics. By building up the MWNT bricks, nano-scale device structures, which cannot be fabricated from three dimensional bulk materials, can be constructed. For the application of carbon nanotubes to molecular electronic devices, it is very important to control the contact resistance between metal and a nanotube. In order to get information on the origin of contact resistance, we have studied material dependence of the electrical transport in metal/MWNT/metal structure in metal-on-tube configuration. Furthermore, for the device construction, the nano-bricks need to be cut to fit to designed structures. We demonstrated an etching process to cut the MWNTs into three pieces for a single-electron transistor (SET). The SET is a useful device to show that the constructed structure has an expected small element. In the MWNT-SET, we observed the Coulomb blockade effect with island capacitance of 4.2 aF at 4.5 K. The observed Coulomb blockade effect meant a quite small island was formed in the MWNT.