I had a scrap swatch of felted knitting hanging around in my stash which I had used to needle felt on. (View my efforts here.) I cut a rectangle out of that swatch allowing for the width of my camera plus a 1/2 inch seam on each side. I made sure there was enough length to wrap the rectangle around the camera down the front and up the back with extra length for a generous flap.
I used the blanket stitch to seam the sides and trim the flap. I found this tutorial helpful to figure out the blanket stitch. If I ever really did...
One of my lovely vintage buttons closes the flap. I just cut a whole in the felted wool for the buttonhole.
Here's the back.
You don't have to knit and felt your own fabric like I did. Abuse an old wool sweater in your hottest washer water and use that for your fabric.
By the way, the strap of your camera will stick out from the side of the flap, so you can carry your camera using the strap while it's in your felted case. I couldn't show you that because I only have one camera!