This is a harness I designed for use with cosplay wings, originally for a Suigintou cosplay but can probably used for any character with wings (of a reasonable size).
There are 4 holes that go through the harness horizontally, where a wire hanger which becomes the "skeleton" of the wing can slide all the way through. Then the hanger is bent back around and inserted into one of the other holes to fix the wing into place. See images for an example. This was intended for traveling, as the hanger can be unbent and removed, allowing the wings to pack down to nearly half the size after disassembly, and re-assembled whenever needed. The wire hangers I used were measured to be about 1.9mm in thickness and were a tight fit. I suggest sanding the hangers if they have been painted, since the paint can scratch off inside the holes and cause them to get stuck. See links below for the hangers I used.
It has mounting points on each corner for up to 1/2" straps, which can be attached to any matching set of adjustable rings and a buckle, similar to a backpack strap. For larger or heavier sets of wings you may need to scale up. See links below for the straps and rings (the buckles I bought locally at Jo-Ann)
The wings are created by cutting adhesive crafting felt in the shape of the wing and attaching it to a wire hanger that's bent into a frame to support it. If it's a bat wing you could just be done after attaching the felt to both hangers and inserting the wire into the harness. For wings with feathers, you can hot glue feathers to the felt, starting at the wing's tip and layering the fluffy parts of additional feathers in a way that hides the quills and hot glue.
I printed this on my DLP/SLA printer... I do not have an FDM printer, so don't know how easily it will print on those. I have included a version with heavy supports, which fits in the build area for the Anycubic Photon. I used Siraya Blu resin, which has a higher strength than typical UV resins, and it held up fine and showed no wear after two long flights and two days of cosplay use, even in large crowds and when bumping into doors/obstacles occasionally.
Siraya UV resin
1) Sand down the edges of the harness with your preferred sanding tool
2) Clip 2 wire hangers to the correct size to form the skeleton of your wings, allowing about 8-10" to use for locking the wings into the harness.
3) Sand about 8-10" at the end of the wire hanger, if the hangers are painted. They should measure about 1.8-1.9mm in diameter.
4) Insert the hangers into both of the wire holes at the highest position on the harness, so that about 3-4" sticks out the other end
5) Bend the end of the hanger back around and insert it into the bottom hole on both sides
6) Bend the hangers into the desired wing shape
7) Attach adhesive felt to both sides of the hangers, cut into the desired wing shape
8) Attach feathers to the felt wings with hot glue, layering the feathers over top of each other to hide the quills and hot glue
9) Cover any leftover visible wire with some additional felt and feathers if needed
10) Loop some 1/4 - 1/2" straps through each corner of the harness
11) Attach a buckle or adjustable strap tri-rings to the straps so the wings can easily be worn/removed, and adjust as needed. The straps should be adjusted to fit tightly, so they will not flop around while walking.
To disassemble for travel/packing:
1) Unbuckle the straps and place the wings face down onto some kind of workspace (you will need some room)
2) Pull the end of the wire hanger out of the bottom hole for one wing
3) unbend the wire and make it AS STRAIGHT AS POSSIBLE. Any small bends in the wire will cause it to get stuck later.
4) Pull the wire slowly back out through the top hole. If there is any heavy resistance, stop immediately and push it back out and re-straighten.
5) Repeat for the other wing