Need some help on a sewing project. I'm recovering the foam pads on two car camping cots with 300 denier cordura. I could turn the cordura inside out, overlap the material a 1/2" along the length and run a line of stitches end to end. Then turn the material good side out, put the foam in place and sew the ends closed with 3/4" nylon webbing for binding. Is that a good approach or is there a better way?

That's probably how I'd do it but that's not saying it's right. Is the cordura coated. If not then you may need to do something to stop fraying.

If you do a standard seam with right sides together and a 1/2 inch seam allowance, and then turn it right side out, the raw edges inside will not fray. OR -

Work with right sides of the fabric together. I would make a long cylinder using a regular seam for the long lengthwise seam and then again with right sides together, square off the bottom end, closing it. I would close the top buy using a double fold edging seam to trap the raw edge and then neatly fold and use Velcro to close or even hand sew the top shut.

It might be hard to explain. I was thinking I have to get better at making drawings and taking photos so I can show rather than explain.

If you want to get fancy - I hope this makes sense. You will use 2 flat rectangles and an edge piece. Start with 2 rectangles the size of your matts plus a 1/2 seam allowance all the way around. Cut and seam a thin strip that represents the thickness of your pad - plus seam allowance. Put a long zipper in the middle of the thin strip. Then seam the strip to each large rectangle - one at a time. Fold and roll the foam, insert and unroll while working into place.

Ok, so this maybe too much for on-line without a video.
Cushion Video I don't think you need the cording she is showing. There are a couple of videos on line - check it out. Or call me. Send an e-mail. I am getting into winter projects.

Well done video, I understand now what you meant about the two flat rectangles with the sides as wide as the foams thickness plus the seam allowance the video called boxing. I don't think I would need the cording either. That would make a good looking cover. I might try it that way, it will be a challenge for me but it might be something I could use in the future to.

The corners can be difficult - the zipper will be easier than you think, but, I would suggest a small project to try the method first.

With the foam pad only 1 1/2" thick I decided to just wrap it with one seam. I marked a line 1/2" from the factory edge and was able to sew right on the line making it easy but capping the ends with the nylon was harder, holding the top and bottom edges together with the nylon wanting to slide around.
I also replaced the cot material which had seen better days with pack cloth edged with nylon and put grommets in for the springs to fasten to.

Nice job - looks like your bottom sheet will support very well.