Disclaimer: I have already been awarded "kook of the millennium" several years running....now that's out of the way.
A few years ago I built this "paddle trainer" at the time there was no gym near my house and I would use it a few times a week to stay in shape between weekend swells or get ready for trips etc bc unfortunately I don't live at the beach.
Since making it, 2 gyms have opened near me and I find I don't use this machine. It is SUPER heavy duty. All 1/4" marine grade aluminum and 1/2" stainless hardware..it's ridiculously over built bc I do marine construction and I used spare boat lift hardware and pieces to construct it. Harken pulleys and stainless fitting throughout. I sewed all the straps, seat covers etc. It is 100% custom. Sector 9 skateboard wheels are the rollers to give it a little wiggle to force you to balance on the board as with paddling a real surfboard. It could live outside but I keep it in my garage. It can break down in many pieces but it will not fit under a bed etc as it is fully welded main beams If you have ever seen a commercially available VASA trainer those things are a joke compared to this.
So now I would like to sell it or trade it, but I just don't need it with the new gyms in town and I can't bring myself to cut it apart for scrap bc I had so much time and $ in making it. You can do millions of functional exercises on this thing, not just paddle. I can send more pix upon request but here is a link to a brief Youtube video of it, please excuse the terrible video it was my iPhone propped up on the hood of my truck so the volume sucks etc: