I have had good luck purchasing the nut for an acoustic guitar and using that as the saddle, what you are calling the bridge.  The saddle (bridge) is what transmits most of the string vibrations to the soundbox which in turns amplifies the sound.  Your choice of material will influence the sound of your dulcimer.  Yes, wood works.  Softer woods will produce a softer sound with more overtones.  The harder the wood, the crisper the sound.  Some musicians will use very hard substances, including brass, to get a sharp twangy sound.

My personal favorite is to purchase a guitar nut made from bone.  (Try ebay, less than$5, less than $1 if you can wait on shipping.)  You will need to cut slots for the strings, in a pinch a common hacksaw will work.  The clean sound produced will reward your efforts.

Thanks to all of you. I now know what I have to do.

I have 2 Warren May dulcimers and a Ken Hamblin...........all needed new floating bridges............got a couple of chopsticks and cut the square end, sanded them level to proper height, notched the little stinkers and they worked just fine.  You can also go to a craft store/hardware store buy a dollar square dowel and shave a triangle piece off it, cut to length and notch it............ tune the middle string to the octave, angle it for the others and tune the rascal up........there should be a piece in this forum by pristine2 that will tell you how to do that............have fun. 

Like KenH I searched Google Images for pictures of Richard Wilson dulcimers.  This is the only link I could find with a close-up of the tail end of the dulcimer showing the bridge.  You may have to sift through the pictures of the dulcimer to find the one with the close up of the bridge.  Incidentally, the bridge looks movable and appears to be held in place only by the string tension.

https://reverb.com/item/2775553-1989-richard-denise-wilson-diamond-designs-hearts-dulcimer-like-new-with-case-paperwork

I'm not sure if all Wilson dulcimers had similar bridges, but this one looks like it was made from maple.  If this one is any indication, Richard probably used whatever hardwood scraps he had left over after making dulcimers.

At one time I had one of their dulcimers, but I couldn't find a photo of it in my files. If I recall correctly it had a triangular shaped bridge and was made of walnut or rosewood. I'll try and do some more searching to see if can find a photo.

Okay, I was wrong. From the photos I found on the internet the bridge was rectangular or square in profile rather than triangular. It looks like the bridge matched the wood of the fretboard.

Ken

"The dulcimer sings a sweet song."

Skip's instructions are good, but it would be nice to see  a picture of the dulcimer, and a close up of the nut.  Was the original bridge wood or some other material.   Basically you make a wedge about 3/8" tall by 1/4" wide by 1-3/4" or however wide your fretboard is.  

You couldl probably make it yourself, which is pretty easy. Just about any hard material will work, a threaded rod, hard wood, hard plastic, corian, etc, as long as you can shape it. Start with a piece 1/4" thick x 3/8" high x 1 3/4" long. The 3/8 will be the fret board to string starting dimension, it should be a bit higher than needed to create a nickel space from the top of the 7th fret to the strings. Taper the length by sanding on the 1/4" surface so one of the 3/8 sides is about 5/16 or so. Use a triangle file or nick the sharp edge on the 3/8 side of the tapered edge for the strings [ match the slots on the nut]. They don't need to be very deep, just enough to locate the strings. The 3/8 side is the one that will face the nut. Sand the bottom [opposite] 1/4 surface, keeping it square, until you get the nickel spacing. I would keep the nickel space on the plus side [about the thickness of a credit card] to allow for string wear-in. Sand the ends to fit the width of the fretboard. Done. 

I have a nice Richard and Denise Wilson dulcimer that's been sitting unplayed for years because its bridge has been long since lost. It's a simple floating bridge. Is a replacement available or does it have to be hand made? If I need to make it, can anyone give advice on shape, material, etc? Thanks for any helpful information.