WOW
I'm Pretty certain that it will be listed on one of the Patent sites with a diagram
I've tried some big Uk paint makers with no Joy (I know what you mean) They reverted to plastic tub/lids for the smaller quantaties
and the 'openers" faded away into obscurity
Try keywords like "Can openers" on Froogle (links to Google) or" tin openers" and set the price high to how...and there is a faint chance that something is listed

Another Possible to try and Not many people are aware of this service, is to try the BETA search page at Google Suggest...
Which is simplicity itself

Basically you do nothing just start typing and Google throws matches at you from its database...Very reliable up to 3 keywords then it gets confused
All you do is click on the Google search button
www.google.com/webhp?complete=1&hl=en PS I forget if you need a Google account to access this service ...But my advice is ...Go for it and All the Programs on Google are now unlocked to you including the Versatile Gmail Program

Your screename becomes your Gmail screenname If and when you want to try that service out
https://www.google.com/accounts/NewAccount