When I got the key lock for the forward baggage compartment, it came with two sets of locks and keys so I repurposed the second one as a canopy lock. Nothing fancy and it's certainly not going to stop anyone from breaking into the aircraft. I still have mixed feelings about it when I consider the work that went into the canopy. Would I rather they just steal my avionics and not break the canopy or would I rather they break the canopy and steal my avionics anyway? Catch 22.
I mounted a square aluminum block on the side rail and you can see how the locking lever comes down in front of the block.
I did mine similar to Carlos151, but used aluminum angle instead of blocks. I also added a second stop a few inches aft of the fully closed lock so I could lock it with the canopy open about three inches. It helps keep the interior a little bit cooler on a hot ramp while I have my $150 hamburger
Another idea is to design your instrument panel so that you can quickly remove most of your $$$ avionics and throw them in your flight bag when forced to leave your plane on the ramp when staying overnight away from home. They can't steal them if they are in the motel room with you! Not much need to lock the canopy if the avionics are not there.