That second video was fun to review. I had seen a report about that young man before. They did not demonstrate j or z, maybe there just wasn't time.
Where to start? I guess you want to make a glove like he made. I would start my search for the sensors in the gaming world or search on "glove with sensors." Here is one of the first hits:
Sensor Gloves-Fernando Kriete
There is certainly educational value in trying to replicate what the young man did with finger spelling, but I suggest you go back a few steps and ask yourself seriously what you are trying to do. If you want to invent
something useful, replicating that work is not the answer. It has already been done. Moreover, there are easier and quicker ways for a deaf person to communicate with someone who is not deaf, such as texting or using a pencil and paper. If on the other hand, you just need a project to turn in, the links you get from Google should help.
John