Depending on the diameter, I like aluminum crutches from a thrift store. They have far too many and I either get them for $2 a pair or sometimes am told, "Take as many as you want, for free." I drill out the rivets and use the tubing for frames, lightweight tripod seats, and various projects that come up. If you don't care about the weight (gasp!) there are click-stop settings at the bottom with indents every inch for about 10 inches. For testing tents and tarps in the backyard, that flexibility could be sweet and let you get your lengths dialed in before cutting or ordering expensive carbon fiber poles.
Also, I can often find old down-hill ski poles in aluminum for $5/pair at the thrift store. Those are a little thicker walled, but nicely tapered at the bottom end, meaning you can find whatever ID/OD you want based on where you cut them.
You can also use them as the spikes on Sauron's armor:
and Klingon disrupters (much lighter bear protection than a .458 rifle):