How can I make my own snowshoes or fitness equipment?

Anybody have any good ideas on what one would need to make their own snowshoes and/or rowing machines? Basically a snowshoe looks like a shoe or a boot with a tennis racket underneath. I’m really into winter sports now, and rowing and it seems like a good way to save money if one knows what they’re doing. I also see that with snowshoes you get a better upper body workout, if you hike using the poles that come along with it? For a rowing machine, I researched how they are designed, and the site mentions using a fly wheel and attaching it to wood?