I have never obtain an Electroporator for my home-lab. Because it's very expensive, I'm trying to create a diy cheap version for myself. In all commercial design, I see that we need to put the sample to a 0.1cm-0.2cm cuvette to doing an electroporation, can I just replace it with an eppendorf plastic tube and put my 0.1->0.2cm alumium electrode inside?
Generally I would advise against making a home-brew electroporator: the voltage needed for electroporation is so high, that even with professional equipment you can easily get arc lightning. In an self-built device that would pose a serious fire hazard.
However even theoretically there are problems with the design you propose:
1) It is important that ALL bacterial cells in the cuvette get exposed to electrical field induced by the high voltage spike. If you use simple electrodes you will only affect the few cells directly between them, which will drastically reduce efficiency of the electroporation. For your design to work properly you would need electrodes that exactly match the dimensions of an eppendorf tube to make sure all bacteria will be squeezed between them.
2) With your device you can only do one electroporation, then you have to thoroughly clean the electrodes. This has to be done for two reasons: first you don't want any carry over bacteria (or as Chris pointed out DNA) from one batch to another. Secondly the electrodes need to be clean of any salts (or other molecules that increase conduction in a solution) to prevent arc lightning between them.