I don't have any pics to post but I'm using some 3/4" strips of velcro. I've got a strip of the 'loop'
side of the velcro glued to the grip and a 5" strip of the 'hook' side with one end looped over the clutch lever. When I'm riding it just hangs there, hook side away from my knuckles. When I need to 'lock' the lever I can lift it over with a finger & stick it down to the grip with my thumb.
I don't put much faith in the 'spring pin' lock idea on a bike that vibrates the way these motor/bikes do.
Slightly off topic but still clutch lever related. On my mountain bike build, I cut about 1 1/2" off the end and mounted it 'above' the grip. Other than the need to lift your hand off the grip to squeeze it 'down'
it seems to make using the front brakes easier than 2 fingers on the clutch & 2 on the brake.
Never know when you may need to hit both 'panic levers' doing 25 mph on a trail.
I'm done typing, so your done reading. Let's Get Riding!!!