Is anyone thinking about building Walsh drivers?

Mapman-
I'm surprised The new Ohm management hasn't jumped on this myself. Infinity crossed at 10KHz, much higher than the "new" Ohm's 8 KHz.. Ohm did license the tweeter to Infinity, but it was probably done during the old regime. Maybe they forgot. The Infinity seems to have gotten a measure of critical acclaim.
The high crossover point fits Ohm's current model, and the offers the advantage of being co-incident to the primary driver's axis. The Infinity had 4 crossover points, three of them in the critical presence band, and moreover it's location on top of a larger rectangular surface without a doubt caused numerous diffraction problems.
I have listened to both the old "A" and "F" models set up properly, and personally, I think that "stuffing a pillow" behind the driver as Ohm is presently doing is not the way to go.
As far as electronics go, you are preaching to the choir.

"I think that "stuffing a pillow" behind the driver as Ohm is presently doing is not the way to go."

I think this is the standard configuration provided to enable speakers to go closer to rear wall than full omnis otherwise and allow the speaks to fit into more peoples rooms like other speakers more easily.

That may be why they pass on the omni/walsh style tweeter. I'd like to see it though if possible in order for the dispersion characteristics to be similar top to bottom regardless of whether full omni or not.

I imagine cost management is a factor in the decision making process as well. The tweeter they use sounds very good. A "custom" Walsh style tweeter would likely add cost. Maybe a premium model of some sort with a separate Walsh tweeter might fly and still come in for a lot less than GErman Physiks, mbl, and their ilk.

But I also suspect that the niche high end market is not something OHM is really all that interested in, at least in the US, although they have started to market overseas in GErmany and elsewhere I suppose where their products can compete with the mbls of the world in a larger market for much less I guess.

OHM does do full omni versions for surround sound systems normally I believe where the sound absorbing materials inside the can are omitted.

I can see your point concerning close wall spacing. The omni's need a lot of room to breathe, and creating the correct acoustical environment is black magic a lot of folks would just as soon avoid.
As for the tweeters, they take a lot of skilled labor to build. It's not something you can pop out of an injection mold, and the key to profits these days seems to be not paying craftsmen or worse, farming it out to the Pacific Rim.
One of the ESL companies, I believe it is Acoustat, moved their production from the UK to China to contain costs. The Chinese company immediately started selling a knock-off with a different name for about 1/3 the UK price. The Chinese seem to be very challenged when it come to intellectual property

Mapman... You can mount a conventional cone driver backwards firing down, but it isn't at all like a Walsh driver.

The angle of the cone and its material must be such that sound propogated down the cone material is delayed by a time that, at every point down the cone, matches the delay resulting from the angle of the cone. (Sorry I can't explain that better). This is the key design feature which enables its superb phase coherency, as evidenced by accurate reproduction of a square wave.

Eldartford,

I'd say you are correct in terms of how a properly designed Walsh driver operates.

My understanding though is that Lincoln Walsh invented the principle, but never implemented a specific commercial design himself, though he was involved early on with the first early OHM products, something that no other makers of Walsh drivers can claim.

SO when I read that any conventional driver can be configured to operate as a Walsh driver (though most likely not a good one unless the principles of designing a Walsh driver are applied and realized properly somehow), I find it hard to argue. The quality of the resulting sound produced in the end based on applying the principles is what matters.

I read about people implementing their own "Walsh" type speakers using otherwise conventional drivers, but have never heard any, so I could not comment on the results achieved.

If it walks like a duck and quacks like a duck, it's probably a duck, but still not all ducks are created equal!