Have seen a number of questions over time about how to assemble a euro profile cylinder, mostly with how to keep the driver pins in place while inserting or removing the plug. This is based on what Femurat has said before.
Wanted to take apart a Papaiz lock recently. I was having a devil of a time reading impressioning marks, and decided to disassemble the lock and make a key that way. While this is not precisely a euro profile, the clip works just the same.
Will show the lock detail first. (Only 3 pictures. Deal with it!)
The lock - Papaiz 5 pin

Field stripped. Yes - the key blank is filed on both sides and the bottom so that it fits the lock.

The Pins - the very rounded ends of the key pins explain the difficulty in impressioning.

The clip - made from windshield wiper insert, filed down to fit in the bottom of the keyway. I find the bend at the bottom to be important for keeping a snug hold on the lock cylinder.

Pick the lock, and turn the keyway 180°.
Insert the clip as shown. I use a diamond rake to press down the driver pins so the clip can slide into the lock.

The clip fully installed:

Slide out the plug!

Note how the clip stays in place on the lock cylinder. It sticks out a little bit in this picture because I made it for a 6 pin lock, and this is a 5 pin. Could not remove the cam at the back of the plug with the clip fully inserted.

Here you can see the clip holding the driver pins in place.

To reassemble the lock, place the springs and driver pins into the lock body, and put the clip in, using a diamond rake or hook pick to press the drivers down for the clip to fit over them. Then scroll up to reverse the process.
Hope these pictures help those who have been wondering.
Gordon