Here is the turned part: It is ½” long (about 13 mm) and has a tiny tapered through bore.

And here is the reamer used to make the bore: It is ground in-house from High Speed Steel, has 3 flutes and is 0.022” diameter at the tip (approximately ½ mm).

The reamer inserted into the part

Laser welding the inner tube to the nozzle.

Laser welding the outer tube. For more regarding laser welding, follow this link.