Extra frame tubing for grow tent?

I have a grow tent that uses 16.5~mm diameter tubing for the frame, is there anywhere I can pick up additional tubes to make shelving or add in more structural support?

I'm using my tent for 3d printing and I'd like to add in a filament spool holder mounted above the printer, along with mounting a smoke detector.

PVC with holes in the end and zip ties

Stretcher bars or by hollow round stock online and 3D print connectors

Gemtree said:

PVC with holes in the end and zip ties

Click to expand...

Yeah PVC is the most cost effective. If you're able to "notch" the ends of the PVC, then you can just pressure-fit them between two of the tent frame poles.