I wouldn't bother trying to make an apron - if you still want one after reading the other threads. I bought one from Creek Company and it works well. My friend made his so ... first he bought some mesh (but it isn't vinyl coated so he has to watch his fish hooks near it). I found better stuff in the auto section of appropriate stores since similar material is used for non-slip trunk mats. Large (replacement) minnow dip nets might also be the correct material. Then you cut it to shape, seam the edges, reinforce the corners, add light shock cords with clips on the end (maybe on both ends if you put loops on the corners of the apron!) for attaching to your toon.
Hopefully you have a model/template from a friend or made your own template first so you don't have to make a second 'better' apron. Probably less than $25, not a lot less, but a lot more time shopping and constructing so not worth it IMO.