Pack Battery Holder for 18650

I've designed this battery holder to help bench tests where you need 3 18650 batteries without having the contact springs on the poles of each battery.

In the cavity of each cover can be made the serial or parallel closure according to the need, (see detail in the photos) where the own wire plays the role of the contact springs, making this battery holder cheaper, practical and functional.

For assembly it will require 2 M3x10mm screws, some pieces of wire and 2 metal inserts with M3 thread