You will probably need to cut the canvas and spines to fit your tank, and might have to tack it with aquarium sealant at each corner of the divider. I had to glue my store bought divider in place because it came with metal clips which made it so my hood wouldn't sit on my tank.
I am sure there is one on this site somewhere too. I tried to make a post gathering information like this so people could use the info on a variety of DIY fish things. I just found this one. I will add this site to that post too. TY for asking about it. :)
The above link has good pics it's just plastic needlepoint canvas and report spines, they come with those clear plastic sheets you slip paper into. You can find the needlepoint canvas at craft/hobby stores.