Coin holder for 10 x 1 Euro / 1 lv

I wanted to store some coins for car wash machines in my car, but don't like to hear them on uneven roads and pot holes. So I found magonegro's design (http://www.thingiverse.com/thing:1475853). I wanted to add a window to see how many are in there so I redesigned it. I made it as small as I can. It holds up to 10 coins (Bulgarian 1 lev is the same size as 1 Euro or a little bigger so Euros will also fit). The spring minimum length is about 7mm and expands to about 20.
There were some finishing