Building a stem. What tubing to use?

[BigPoser]

I've been wanting to build a stem (or several), but I've not done it before. Is there a particular wall thickness that I should be using to keep things safe? I've got a lot of excess tubing pieces laying around from various ST, TT, DT, etc that I've cut to length. Safe to use these? Any advice you can throw my way?

Thanks in advance!

Brandon

[progetto]

.8 minimum, 28.6 dia.

[BigPoser]

.8 minimum, 28.6 dia.

Thanks.