portable straight key

A straight key that could be used for portable operation. I made 2 versions. One works without bearings and that works pretty smooth, with a little sanding the parts that fit together. The 2nd version needs 2 ball bearings 3x10x4. Those worked great for me: http://eu.banggood.com/Wholesale-Warehouse-10pcs-623-ZZ-3x10x4mm-Deep-Groove-Ball-Bearings-Miniature-Bearings-wp-Eu-81182.html
The lever is designed to have a 3.5mm gold contact bullet connectors fitted in that is used as 1 of the 2 contacts. Something like that: https://hobbyking.com/en_us/polymax-3-5mm-gold-connectors-10-pairs-20pc.html. You can use male or female. Does not matter.
The counterpart is a contact broken out of of a Deans T-plug, like that one https://hobbyking.com/en_us/nylon-t-connectors-male-10pcs-bag.html
You can also use something different that fits into the slot a made for easier positioning.
As socket for the cable I use a 3.5mm socket. I bought mine from Amazon. https://www.amazon.de/gp/product/B008SO06TU