Want to make my first LED string need some help

[DarthMike]

So I have made what I think is a pretty cool looking hilt using some hardware store supplies, and I am ordering the 1 inch thick walled blade now. My blade holder is set up specifically to tightly fit the blade and allow room for the wires to pass down and through the hilt to my power supply. Here is where I have hit a road block. I happen to have some 18350 li ion batteries laying around and was hoping to use them for this project. Also I wanted to gut a toy saber for the sound effects. What information do I need to know so I don't over/under power my components? I have been researching heavily but can't find much information on using these 18350 batteries which are 700mAh 3.7 volts. I'm not decided on how many LEDs to use either and would like to add accent lights and a switch with an LED inside of it. Any insight would be appreciated. The physical building is easy for me and I havr a good understanding of building circuits and soldering I just need to figure out how to power this thing and if I will need to add any resistance or move to using AA battery packs.