Here are some more thoughts for @slrmagic, after reading further comments.

1. Rear/front thread sizes if you make an "adapter" for use with various "taking" lenses: 72mm is the front thread I would suggest. The best circular diopter option currently is the Tokina ATX, which is 72mm. Any front larger than 72mm would risk vignette with the Tokina ATX. Also, I'm no rocket scientist, but I think if you were to make the back thread 72mm, the front thread would have to be significantly larger than that. I'd try to keep the rear thread a bit smaller.

2. A unique approach that just might make everyone happy: 1.33/1.35X anamorphic lens with oval iris. Best of both worlds. I did some serious internet digging on the oval iris concept several months ago, and I'm pretty confident that it would be possible to make an adjustable oval iris (that is, it is not fixed aperture; it has blades and can be stopped down, remaining oval). Therefore, you could make an anamorphic lens with a 1.35X squeeze up front, and make up the difference between 1.35X and 2X out of focus "smear" via an oval aperture. What you'd end up with is an anamorphic that flares lightly but not too much, that desqueezes from 16:9 to 2.39 without the need to crop, and that still delivers wonderful out of focus smear 100% on par with that of 2X anamorphics.

3. Also, I don't know much about them, but I don't think rear anamorphic elements have been mentioned yet. As far as I know, they don't flare at all . . . but it may be more cost-effective to squeeze the image with a smaller set of optical elements near the back of the lens, rather than with a large set of front elements . . . just something you could look into. Flares can always be achieved with a flare filter.

P.S.

Just the fact that as a forum community we are having this conversation with a manufacturer is incredibly cool. @slrmagic mad props.

(also, I'd reiterate what others are saying concerning lens mount. Providing it doesn't significantly effect price, a "Super 35/APS-C" EF-S mount lens will significantly widen your target audience.)

In any event. Someone who makes a very inexpensive anamorphic adapter will sell a ton. how many of us hunted out old Anamorphic and projection lenses for a lot of $$$. How many times did you actually use them? If you want to spend $300+ you can buy them on ebay. But a small light weight adapter for a Lumix lens that already has auto-focus is an untapped market.

@apefos The problem with the extending barrel is not that it will vignet, but the fact that the whole adapter will be pushed forward as you zoom. That makes it very hard to use a mattebox and to fasten the adapter to your rails.

To solve the problem of weight and avoid damages on plastic lenses the anamorphic adapter can have an aluminium base, a flat aluminium from the bottom of the adapter to the bottom of the camera and screw it in the camera tripod screw hole. and this aluminium base can have another screw under it to fit on tripod or in the rails/mattebox. this base can be removable and can exist different sizes bases for different lenses or it can have some kind of slider to make the adapter go front and back, also useful for zoom lenses when it extends while zooming. all problems can be solved with some imagination and design.

@disneytoy I'm been looking for the lens, too. 8mm Berthiot S.T.O.P. "Baby Hypergonar". Some say there are only 50 units ever being made?

15 votes only for the anamorphic squeeze. Can we do better than that? http://www.easypolls.net/poll.html?p=50477872e4b0ce84916c0ecc

Is the protruding front of a zoom really a problem though? Only if you plan to use a mattebox and zoom while shooting. Personally I´d never do the latter so it would not make much of a difference. Just the normal hassle of changing lenses.

There would definately be a market for a cheap plastic adapter. For me? Don´t know, would depend on the IQ.

@slrmagic We most certainly want any vignetting to be in post production if at all possible. It is easy to add a vignette to footage, but much harder to remove it if it was put there optically. A vingette is effectively removing information from the image. If we want to remove information, we can always do it in post. However, we can't get any new information in post, no matter how hard we try. If left with a choice, always take the option that yields a more "perfect" or neutral image on the sensor.

If people really want optical vignetting, it could easily be done with a vignette filter (I don't know if anyone makes such a thing currently, but imagine an ND Grad with a vignette pattern), or maybe even with some empty filter rings that stick out far enough to enter the edges of the frame.

In spite of what @disneytoy and others say, I think a cheap plastic adapter is a bad idea. Yes, no-budget filmmakers will love it, but no one else will, and anyone who has actually tried to acquire a decent anamorphic lens will know that finding one that covers S35 is nearly impossible at any price point. Projector lenses will, but they're not designed to be used on cameras and it shows. There is a HUGE gap between the plastic lens/toy camera level and the next practical anamorphics ($5K - $10K range). Yes, there are a few lenses that cover that gap - mainly the ISCOs - but all are extremely rare and, by this point, quite old.

@jackdoerner I agree about a cheap plastic adapter being a bad idea. It would be downright silly to have a cheap and flimsy solution for the hobbyists on one side of the spectrum and an incredibly expensive pro-solution on the other side of the spectrum, but nothing in between for the semi-pros and the low budget professionals. The need for anamorphics is huge in the middle range right now, not in the lower range! I don't see many hobbyists screaming for anamorphics...

@slrmagic Slight vignetting is ok to me... but not too much. If you guys are planning to make a fixed focal length anamorphic lens, I'm pretty sure it can be as big as Nokton 25mm 0.95. In fact the size doesn't really matter as long as it can be easily controlled with follow focus. Just make sure it has m43 mount :)

Also I don't think anamorphic lens has to strive for optical perfection, but it must have its own unique characters and good center sharpness :)

Certainly, you´ll in time need to decide and assess what you can - cannot do. Either you go the cheap route and make a lens/adapter that performs well for the money (could be with a prism, plastic elements or whatever) or you go the "cheap" high end route and think about what you need to achieve to sell lenses / adapters for that market category. In the first instance, build quality is secondary. You will have customers as long as there´s a desire for an anamorphic look. In the second instance you can´t cut corners anywhere and you´ll need to work long and hard at it, but if you succeed you will no doubt have a solid base of customers since there is so little competition at sub 5k price point..

when i talk about an affordable price adapter i do not mean plastic or toy design. If there is plastic, it can be just in the housing. The lenses must be glass and coated, no vignetting, no soft corners, no barrel distortion, no chromatic aberration. IQ is a must. I think it can be done at 300 usd price range. Lets say, not consumer, not professional, but prosumer... like GH2 is.