(QLF means sending Morse code with your left foot)
My wife got a fine new sewing machine, so I could take the foot pedal from the old one. It makes a nice CW key for left foot sending. I just added a keying cable and that's it.
There are two main ways how to use a foot pedal CW key.
First, by flexing the ankle, as seen in my original video from year 2007:
Second, you can keep the ankle stiff and move the whole leg instead, by using thigh muscles. I found this is the easier and better way to send decent QLF code. Here is my newer video from 2013 (as you can see I do have changed my socks meanwhile), when I worked the SCAG Straight Key Day: