DIY tank dividers?

Okay, so you don't want to use silicone on the craft canvas. Understood. Now, this is even easier. Cut and trim your canvas to size (must make a pretty tight fit, but leave about 1/8-1/4 inch gap on each side). Next. Get some suction cups from your aquarium shop. I like to use the 3/4 or 1 inch diameter ones. Now, get out your sharpie or permanent marker and sharp scissors. What you want to do is cut the plastic canvas so the suction cup fits nearly flush when it is perpendicular to the canvas. This is a hard one to picture so I'll elaborate. Hold the canvas in the empty aquarium where you wish to divide the aquarium. Place the suction cup on the aquarium wall and slide it over to the plastic canvas (a spray bottle of water helps!) Take your marker and trace the profile of the suction cup onto the canvas. Cut out the silhouette that you just put on the canvas. Now put the suction cup in the canvas cut out, half on one side, half on the other. Use aquarium grade silicone to secure the suction cup into the canvas. Allow proper drying/curing time. Repeat in as many places as you believe it will take to secure the canvas. Just a side note... if you take your extra canvas scraps and super glue them to the bottom of your canvas divider so they make a tee you can bury them in your gravel to add extra stability. Always keep in mind that Bettas are jumpers. They are extrodinarily good jumpers so you must have a tight fitting cover or other device to prevent your fish from jumping compartment to compartment and fighting with each other. I'm not a big fan of divided aquariums for Bettas, but if there is a will, there is a way! :)

Buy a few nylon mesh, like those used for aquarium fish nets, and purchase plastic binders. Cut the plastic binder flaps and mesh so you'll have compatibility the mesh among the two pre-reduce binder flaps. Then silicone glue either one of the binder flaps in combination. The easiest manner, I suppose, is to get a a million inch thick piece of sponge and reduce it into the form of the intensity of the aquarium and wedge it among the two places. You would get a work of nylon and four suction cups to separate the two places.