Hardware help: need some "sticks"

I have an urgent need for some flexible stiffeners I can attach to already-finished banners to keep them from twisting and tangling on their poles; basically, a field fix for something I should have foreseen in the design phase.

I need 12 “sticks” 36 inches long, slightly flexible, that I can permanently bond or attach to vinyl banner material. I am thinking ABS or hard vinyl, maybe 1/4 x 3/4-1 inch, black would be ideal, white would be okay, deep navy blue is probably asking way too much. I’m thinking a combination of “goo” adhesive and staple-through the hem.

Can’t use vinyl adhesive, as printed vinyl won’t take it properly. Can’t insert anything into the hem because it’s flat-welded.

Cheap material, attachment, other solution ideas?

(Detail: the banners are 3 feet wide and 3 feet high on one side, six feet high on the other, with a 45-degree top to hang straight from a standard flag pole. Pivoting pole and mounts aren’t enough to keep the wind from flipping the tail up and over, where the material weight and stiffness keep it from self-untangling. HAVE to fix this in the next couple of days; a stiffener across the bottom seam seems best option.)

Mondo cable ties. They don’t list a price on that page; might have to dip into the actual ordering process to find it. They have other sizes; that’s just the one closest to 36". Downside would be that they might be curved. A guy I know uses these as heavy-duty boning for hoop skirts.

I’m not sure I’m totally understanding, but could you make a frame out of small diameter PVC pipe from Home Depot and zip tie the banners to that?
Home Depot would probably also have long wooden dowels. The kind you see on those little hand held American Flags. You might be able to make those work.

Possibly closer to what you’re looking for would be stick of balsa wood. A hobby shop might have them, but probably not in the lengths you’re looking for.

ETA, what about a sheet of cheap formica laminate (like for a counter top). Then you could cut it to whatever width and length you want.

Balsa wood is light, but not too strong. The laminate countertop material sounds promising to me.

I used to build kites and used both fiberglass rods and carbon fiber rods in their construction. I’m thinking the tip section of a cheap fishing rod might be just what you need.
Maybe something like this : Zareba FRP60 Fiberglass Rod Post, 60-Inch https://www.amazon.com/dp/B00GBVCBYK/ref=cm_sw_r_awd_Lv3yvb0EHVA7Z

Or this: Fiberglass Round Rod, FDA Compliant, Opaque White, 3/16" Diameter, 5’ Length https://www.amazon.com/dp/B00EVC4HYI/ref=cm_sw_r_awd_dx3yvb001RTKV

A pair of wooden yardsticks, flat sides glued together, would probably give the right combination of strength and flex. The banner could be stapled to them, painting them would be easy, and they’re pre-cut to the length you want. Just need to find two dozen of them.

Not clear: these need to be VERY attractive and complement the dark-blue banners if not invisible. They also need to be quite durable, as the banner-flags will be up in New England weather for at least four or five months.

Damn that I didn’t figure out this problem in advance. It was SUCH an elegant solution.

Is there any ready source of ABS rods or bars approximately that size? I’m usually good at mining hardware and hobby catalogs for odd uses, but this one’s stumped me. Right now, half-inch tubing, slotted and held on by three small bolts, is my best thought.

You might try the garden section for sticks for tying plants up.

This might be a little off, but could you just sew or crimp some fishing weights to the bottom?
If you used ones like these and hit 'em with a little navy blue spray paint before you sewed them on they’d almost look like decorative.

Bamboo is strong, flexible and shouldn’t be too difficult to affix the banners to.

You might also like to invest in solar powered LED lights so the banners remain visible at night.

McMaster-Carr has plastic rod in various profiles. For example, they have six-foot sections of half-round acrylic; with an outside diameter of 3.4" one is about ten bucks. It’s clear, so it shouldn’t be too ugly.

Graingers might be another source.

Another idea. Can you fold over the bottom seam so that there’s a loop or tube into which you can insert any heavy material?

They make cloth tubes with BBs inside. They are used to weight draperies. Lead Free Sausage Bead Weight, Fabric Covered, 4/32", 6 YD Pack https://www.amazon.com/dp/B00II8UPWO/ref=cm_sw_r_awd_Xa5yvb05Y2QEE

Maybe those fiberglass sticks they use to mark driveways in snowy areas?

The small diameter you are looking for eliminates most materials as it wont be stiff enough. Carbon fiber arrows might work but they are only 32" long. I would say carbon fiber tubing or solid carbon rods.

Is the bottom seam already finished?

Sounds like you need battens such as are used in sails.

I think a picture would be really helpful. At least a picture of the current project, but maybe a finished one as well. I have an idea as to what’s going on, but if I’m (we’re) at all misreading the OP, our suggestions might be way off base and just wasting time. If a picture isn’t possible, even a generic google image might help.
As a last resort, you might want to go to a banner/sign or Flag shop and ask them for suggestions. I’d wager that flag shops have people asking for flags that will stay displayed even on non-windy days.

Another random suggestion is using your slotted PVC, but than also sewing a dowel into the hem (or attaching it however you see fit). The dowel will keep the banner from pulling back out of the slot without any external hardware.
Keep in mind, PVC from a hardware store is going to have writing on it. Acetone (nail polish remover) or Naptha will probably remove it. PVC cleaner will as well, but it almost always has brightly colored and very messy dye in it.
Also, they do make grey PVC, you’ll find it in the electrical section at Home Depot, it’s for burying wires (it’s underground conduit). Still has writing on it though.

When I read the OP, I thought, “he’s describing battens.”

Battens and boning have to go into pockets, right? That’s not a very viable option (although it could have been, a few steps back). I need a solution I can attach to the outside of a flat, welded hem quickly, durably and as close to invisibly as I can get…