I have some experience making chime tubes.  I once had to replace
a missing tube from an otherwise complete set.  This is how I
successfully did it:

I obtained half-hard brass tubing of the correct diameter (I think it
was 1-1/4 inch).  That is easier said than done, I know.  I was a teacher
of high school Industrial Arts at the time and was able to obtain the
tubing in 12-foot lengths from Broadhard-Garret.

(My 1992 catalog lists "Seamless Brass Tubing, 20 gage, 12-foot
lengths, 1" diam. $71.  Telephone number: (419) 589-1800 Mansfield,
Ohio).

I have no idea where to find tubing more than 3 feet long today.
Small Parts Inc. sells a 36-inch piece of 1-1/2-inch diameter tubing
for about $40.  I do not think one needs to go that way.

The tubing was cut 2" longer than necessary.  It was then chucked in a
lath and faced square.  I then cut a square of brass from flat stock of
the same thickness as the wall of the tube.  While the tube was chucked
in the lathe, I silver soldered the square to the end of the tube using
the tailstock center to hold the plate in place as I heated up the
metal with a gas torch.

After cooling, I carefully turned the plate down to the outside
diameter of the tubing.  Now I had a long tube, capped at one end.
A 3/16" diameter hole was drilled about 1/4" below the capped end of
the tubing for use in hanging.  Hitting the tube at the top produced a
surprisingly accurate chime tone.  All that was left was to tune the
tube to the correct pitch by facing off the other end a bit at a time.

Hope this helps.

Andy LaTorre
LaTorre Orgue Mecanique