Prop Building - Rabbit Ears - How would you do it?

Here's how I'd do it - I'm not a professional prop maker, but have made glowy props in the past:

I'd make ear-shaped wireframes out of fairly thick wire (coat hanger would do, for sure), mount the strip of LEDs in them, then sew opaque fabric covers to slip over them - transparent enough to allow the light through, but opaque enough to diffuse the light and hide the structure, maybe some white Lycra or organza. Your ears should be open wire loops, with some extra wire extending from the end (give yourself lots, you can trim it down if you need to). You could put in a few crossbracing bits to give the ears a three-dimensional shape - either using thinner wire wound around the main wire, or thick wire soldered on if you're feeling fancy. Curve them out wards at the back so the ears become slightly concave. You could soften the shape a little by coating the wireframe in hot glue, fabric, neoprene, excess fabric etc before putting the fabric sleeves on - you don't wan to bulk it up took much, but it'll help hide the outline of the wire.

Cut slits into the crown of a hat (I'd go for somewhere near the band on either side). Get a couple of plastic, rubber, or thick leather discs, cut a slit in the middle of each like a button hole - these will go on the inside of the hat and form mounts for the ears. Take the ends of the wireframes and bend them outwards to form a T shape. Squeeze the ends together and push it through the slit in the hat, slip the discs over the T, then release the ends so they spring apart again and hold snug in the slits. Once you're happy with the placement of the ears, glue or sew the discs in place inside the hat (don't forget to feed the wires for the LEDs through, and test it a couple of times first - you don't want to find it doesn't work after you've secured it all) so the ears are held fast and don't wobble about. You'll probably want to put a pad or something over each disc inside to protect your scalp from the ends of the wireframes. You'll likely need to make the T shape a bit diagonal to get the right alignment on the crown of the hat, so work that out first thing before sewing up the covers, since those will need to fit the angle too (don't want any bunching, that'll give the game away).

Run a single wire to the battery pack down the back of your neck and into your shirt, then into whichever pocket is handy - you could even stitch a few little guide loops of thread inside the shirt so the wire stays put. Maybe put a joiner inside the hat, so you can unplug the long wire easily if you want to - it also creates a natural fail point in case something happens (like some wanker pulling your hat off) that minimises the possibility of damage to the whole rig. Depending on how powerful your LEDs are and how long you'll be running them, you shouldn't need a big battery - a couple of AAs or an ordinary 9V should probably do fine. Electronic hobby shops should sell all the bits you'd need, and should be able to advise you about exactly how much power you'll need. You don't necessarily need to use LED strips - you could get a bunch of little individual LEDs and string them together, either in a straight line, or in a loop following the curve of the ear. The fabric you pick will decide how each option will look, but if the individual LEDs are spaced right and the fabric is the right opacity, then the light should be nice and consistent (hell, you could always beg a bit of frost/diffusion from your LX dept and put that inside the wireframe, then put the fabric over it - it'd be tricky, but you could use a thinner fabric that way. It'd be a bit finicky, but the results could be really nice).

Just an idea, I'm sure other folks here will have much better suggestions, though.

Hi! I can't provide much input on the light up part, but I can confirm that using wire frames works out really well. I purchased a pair of Louise bunny ears (Bob's Burgers) from an Etsy shop, and they've held up really nicely using that technique. From what I can tell, the two wire frames are attached to a piece of plastic that only runs between the two ears. They're fully posable and are the only ones I've seen where they actually stand up. Hope that helps a bit!

Edit: I also agree with most everything that the poster above me has said, with a slightly different suggestion. Perhaps buy a hat with a little bit of extra space to mount the batter pack inside the hat? That way, you don't have to fuss with any wires and it's all contained within the same unit. Just stitch a little pouch inside for the battery and tack the wires down.

I'd probably go for EL Wire (the link goes to a peice that is obviously too large for a pair of ears, I'm sure you can find smaller once you know the size you want) for the light. EL setups are very small, and are perfect for lightup costume pieces like this.