Pond seeker, I built the same type of structures you are looking at. I used two different diameters of black tubing to run through the plastic pipes. For both of them I was able to find a drill bit that ended up with a very tight fit for the cross tubing sections. It became somewhat of a chore to get all the tubing started and through the pipe, but it worked fine. I was thinking I would need to run a screw up from below each section if tubing from the pipe into the tubing. I did not. They've been in the pond for over a year, and the tubing hasn't moved at all. My only boat at the time was this old canoe. I don't recommend getting them out to the middle of a pond in a canoe. I didn't tip, but it's not all that easy on the back, as each 5 gal bucket had a lot of concrete in it.
I also wished I would have put a bigger base on the 5 gal bucket. I did have one tip over when dropped in. I went swimming this summer and stood it back up.
The fish are always around them. (I did sink three huge cedar trees in the area also.)


12 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (decreasing), SMB, and HSB (only two have been seen in 5 yrs)
I think that's about all I should put in my little pond.
Otter attack in 2023.