First LED-String Lightsaber - Brightness problem

[TeeBeutel]

Hello,

I`m currently working on my first LED String Lightsaber.
I used 120 of 5mm Nichia red-LED`s , drilled a cone in the head to increase the angle and put them together. I don`t want a scrolling effect on the blade (i use the spark 2 board later) so i thought i don`t need to put the LED`s into segments like many other people do it.
However, when i light it up, the LED`s at the point where I supply the power are the brightest - decreasing going through the ladder. If i do the power-input at the middle of the string, it`s better.

So my question: Am i doing something wrong or has there to be segments?

Thanks in advance

im from Germany btw - sorry for my english