What kayak erg do you have?
I DIY'd it. It's built on top of an old Nordic Track. A few hours of work. Not sure how handy you want to be, but I can send you the info if interested.
I like it enough to keep using it. I don't know what a real one is like, but I don't have an urge to upgrade mine.
Cool, I was thinking of making one also. That would be great if you send me any info.
I think I have your email. I'll send you what I used as my guides and also some pictures of mine. It turned out a bit more compact than any others that I saw.