I made a tube last year. I used horse fence similiar too cattle woven wire but smaller squares. I cut the end so that I had wires sticking straight out, and bent them around to make hooks. Rolled the wired over and hooked it to form the inside tube. I weaved straw through it from the outside. Then I made a bigger tube filled it with straw enough to fit the smaller tube in but be tight. Zip tied them togeather. Next I took 4 inch aluminum angle iron and drilled holes through on top edge. With regular thick wire wrapped the tube and tightened it firmly through the holes. Welded the aluminum angle iron to an old aluminum pole I had laying around the barn. Last year nothing used it, this year I've got a pair on the pond everyday but I haven't seen them in the tube.