Is this a threat to Mul-t-Lok

[datagram]

This is theoretically possible on a modern Mul-T-Lock but it'd be a bit harder to execute than with most of the dimple locks it's demonstrated on. The technique is known as "self impressioning" or "pressure responsive impressioning". Instead of manually making marks and filing where necessary the operator uses a pliable material and the spring bias on components will distort the material until components are set correctly, at which point they should no longer be under spring pressure (or not as much, at least). The main problem is that warding on these locks are lax due to a high number of pins. A high number of components, a reversible key, and warding means that you're going to have to give up something somewhere; you simply dont have enough material to bit and ward both sides of the key. So, warding is thrown out in favor of a high number of components, improving master keying potential and convenience.

Lax warding makes this easy, of course, because you can just stick something in the keyway and go to town. With a MTL Classic/Interactive you have quite a bit of warding directly on the bitting area. Very early versions of MTL Classic had almost no warding and were vulnerable to this type of attack. You can see a photo of one of the early keys on page 9 of the article linked here viewtopic.php?f=91&t=7179

Of course, with the Interactive/MT5/MT5+/CLIQ models you will still have to defeat the moving components and, in the case of the MT5+ and CLIQ, the sidebar.

dg

[elbowmacaroni]

I've heard people talk about popsicle stick impressioning before... trim it to fit the keyway width-wise and then soak. I've not tried it, so I can't really speak to the veracity of its utility, but it might be worth a try. Especially interesting insofar as on the MTLs.