I have the K1EL WKUSB-SMT keyer. I like it a lot. I use it at home and in the field. I would normally either plug it into my laptop or a battery for power. However, I am trying to clean up my act and reduce some of the cabling I have. The keyer will run for months on 3 AAA batteries that stow inside the case. It is a little bit of a chore to change them out due to the 4 teeny screws that hold the clamshell case together. Fine at home, but could become an issue in the field.
I put the batteries in and placed the keyer right-side up in my field box. When I got to the campsite and took the box out of my truck, I heard “dah-di-dah-dit, dah-dah-di-dah” I must have bumped one of the buttons. I open the box and there was the keyer chirping away — with no way to turn it off. Luckily, the paddles were in the top tray so it was easy to hook them up and send a dit to stop the keyer.
When I got home, I scrounged a few parts. All I needed was an SPST switch, some wire, and shrink tubing.

I found an open spot below the paddle connector and drilled an appropriate-sized hole.

A little bit of solder and some heat on the shrink and I’m done.

Now when I travel, I just flip the switch to turn it off. It probably took me more time to write this than to complete the project.
I use the keyer a lot. It integrates with ACLog seamlessly. There is also an app that allows me to program the keyer with a keyboard. I can then save the different message banks on the computer and load the one I need for the trip. I have one for POTA, SOTA, and Field Days. One thing I like is I can slow the CW speed for certain words. I’ll do that with Park ID. Start at 18, slow down for the park number, and then speed back up again. All with the push of a button.
I hope this gives you ideas for your own projects. 73 — Scott