You need:
* Tek Six turret
* hacksaw
* pliers
* rubber bands
* barrel material of your choice (preferably PETG)
First off, you take the turret out of the gun.

Secondly, you remove the pegs with a pair of pliers, (if you haven't already)
Thirdly, you cut the turret so it looks like this

except all the way around
Finally, you slap whatever barrel material you want in there. I haven't tried it but I recommend PETG since it's the most likely candidate to fit.
As a bonus:

I banded my gun!








