Finding a USA company to make these small nylon catch release net bags was a definite challenge. Fortunately I have found a company that offered a soft nylon net bag in a variety of sizes and colors.
To have the best fit in your landing net frame the net bag should be under slight tension when they are attached. I strongly advise obtaining the bag before you build the frame. You can shrink the net bag by briefly immersing in hot water but the effect is variable. They are made in the USA and each net bag is hand-sewn so there is a degree of variation. (I sometimes will over dye these bags to soften the colors when I use them in my nets. Be sure to mix the dye in cold or slightly warm water, you may need to wait overnight for the dye the penetrate).
Please note: because of their small circumference there is more variation in manufacturing. The colors are very vibrant.
22 inch Circumference net frame 8 inches deep; black, red and green
25 inch Circumference net frame 8 inches deep; black, red and blue
30 inch Circumference net frame 9 inches deep; black
33 inch Circumference net frame 9 inches deep, black