http://www.geocities.com/cjsplapp/tension.html
This one was just a basic L shape for Master Locks #1,5 and 40 that I own.
I didn't like the way the tension tool I have seemed to slip every now and then so I thought why not make one that fits the key ways shape so it would be a very positive feel.
I chose a master lock key way first because of its simplicity but I would think this would work for most locks out there wouldn't take long to get a collection going.
I have yet to polish this tool up just some 120 grit sanding to get it fairly smooth.
As for performance I love this it doesn't slip in the slightest and gives a real positive feedback from the lock. So far I have picked all 3 of the locks mentioned above with it several times with no sign of the metal getting brittle.
Made this one out of brick strap(seem to have found a never ending supply of it

I do apologize for the blurriness of the photos, no macro on my digital camera, Ill try to take some with my SLR but I think the general idea is seen in these photos.