Picking tubular locks follows a very similar method to picking pin tumbler locks apply tension and move the pins to the sheer line the only problem is applying the tension to that circular lock.
Sparrows MANTIS is a tension wrench designed to apply rotation tension on the center plug of tubular locks. With the right amount of tension you then can work the pins by pushing down on each one in a clockwise pattern. Just like lock picking work the pins and feel for feedback letting you set the pins and pick the lock open. The nature of tubular lock design is that you have to pick it 2 or 3 times to get it open.
Now here is a bit of a trick - once you have picked it open only rotate it a bit. Take a business card roll it to the size of the lock - tape it up a bit. Now jam that rolled up card into your picked open keyway. Push hard enough to get the impression of those pins on the tip of that card and now you can use that as the key and open it all the way.
The Mantis takes a bit of practice but you can do it.
This is only for the Mantis - use a short hook or paper clip to set the pins