Always felt the toggle switches used for my button box were a bit short so I made an extension that's 26.5mm long and is a press fit into the toggle switch. I'm using an off the shelf toggle switch that is ~10mm long and is 3mm wide at the widest. Since it is a press fit, it's possible that you may need to adjust the hole diameter depending on your toggle switch brand.

I recommend allowing them to cool on the bed for a few minutes. I found when I pulled them off immediately the fit was too snug.